) Is the pressure difference between the oval and round windows the effective acoustic stimulus for the inner ear? by Susan E. Voss Submitted to the Department of Electrical Engineering and Computer Science in partial fulfillment of the requirements for the degree of Master of Science in Electrical Engineering and Computer Science at the MASSACHUSETTS INSTITUTE OF TECHNOLOGY February 1995 ( Massachusetts Institute of Technology 1995. All rights reserved. Author..... Department of Electrical Engineering and Computer Sc..ience............... Department of Electrical Engineering and Computer Science January 20, 1995 "~ Certified by ...... John J. Rosowski Associate Professor of Otology and Laryngology, Harvard Medical School ^ m :7 Supervisor Certifiedby.... ..... ............................... ........... · William T. Peake Professor of Electrical and Bio-engineering, M.I.T. Thesis Supervisor ¢\ n t , n A Acceptedby............... aU Q\ \,-W F. R. Morgenthaler Chairman, Deartmental Cmmittee on Graduate Students INSTITUTE MASSACHUSETTS APR 13 1995 Is the pressure difference between the oval and round windows the effective acoustic stimulus for the inner ear? by Susan E. Voss Submitted to the Department of Electrical Engineering and Computer Science on January 20, 1995, in partial fulfillment of the requirements for the degree of Master of Science in Electrical Engineering and Computer Science Abstract This thesis experimentally tests the common assumption that the pressure difference between the oval and round windows of the inner ear (cochlea) is the only acoustic stimulus for cochlear response. The cochlear potential, recorded at the round windows of anesthetized cats, is used as a measure of cochlear response. The sound pressures at the oval and round windows are individually controlled. A linear model of the response to the two input pressures estimates a complex common-modegain C and a complex difference-mode gain D. The magnitude of the difference-mode gain IDI is found to be at least 20 dB, and in some cases 40 to 60 dB, greater than ICI; to a first approximation the pressure difference between the oval and round windows is the effective acoustic stimulus for the inner ear. This result is relevant both to models of the inner and middle ear and to clinical approaches to the improvement of hearing in ears with no ossicles. Thesis Supervisor: John J. Rosowski Title: Associate Professor of Otology and Laryngology, Harvard Medical School Thesis Supervisor: William T. Peake Title: Professor of Electrical and Bio-engineering, M.I.T. Acknowledgments I would like to thank my advisors Dr. John J. Rosowski and Professor William T. Peake for their constant guidance and support through all phases of this project. The three of us had numerous discussions concerning the experiments and data interpreta- tions presented here. I learned a lot about science and the auditory system through these meetings, and I appreciate all the time spent to meet with me. I also thank John for teaching me to work with experimental animals. John spent several nights working at EPL so that he would be available when I needed help. Many members of the Eaton-Peabody Lab helped with this project - I thank you all! Animal surgeries were performed by Leslie Dodds, Debbie Flandermeyer, Kerstin Jacob, and Tracy Liu. Debbie also assisted with several of the figures in chapters one and two. Discussions with Bertrand Delgutte, Nelson Y.S. Kiang, Sunil Puria, and Bill Sewell were particularly helpful. I thank Mike Ravicz for his assistance in teaching me to use the chamber 2 equipment. This work was supported by NIH grants T32 DC 00038 and R01 DC 00194. 4 Contents 1 Introduction 9 1.1 Ossicular versus non-ossicular coupling ................... 1.2 The pressure-difference assumption. 9 11 1.3 Experimental results relevant to the pressure-differenceassumption . . . 12 1.4 16 Common-mode and difference-mode responses ............... 2 Experimental methods 19 2.2 Stimulus paradigms. .......... .19 ...........19 2.3 Experimental configuration. .......... .20 2.4 Probe-tube microphone calibration ............ .......... .20 2.5 Animal preparation . .......... .23 2.1 Subjects ........................... 2.6 Computer measurements of sound pressure and cochlear potential 2.7 Cochlear potentials and TTX ............... .......... .25 2.8 Definition of noisefloor ................... .......... .26 2.9 Independent control of oval and round window sound pressures . . .... .... .... 2.10 Frequency range. 5 25 27 27 3 Methods of estimating common and difference-mode gains, C and D 31 3.1 Linear fit to the data .............................. 33 3.2 Logarithmic fit to the data 35 3.3 Correlation coefficients. ......................... ............. .............. 36 4 Pressure measurement errors 4.1 39 Calibration errors ................ ................ 4.1.1 Stability of absolute and relative calibrations 4.1.2 Movement of acoustic assembly ................... ............ 4.2 Spatial variations in pressure in the tympanic and bulla cavities ..... 4.3 Summary of pressure error estimates .. 39 39 42 . ................... 5 Results: Stimulus to one window 45 47 49 5.1 Experimental results .............................. 49 5.2 Discussion .................................... 57 6 Results: Stimuli to both windows 65 6.1 Experimental results .............................. 6.2 Model fits to the data: Estimation of C and D 6.3 Discussion ............................... 77 6.3.1 General model behavior ........................ 77 6.3.2 Why is it difficult to estimate C? ................... 85 6.3.3 How much is the estimate of C affected by small errors in pressure measurements? 65 ............... ............................ 72 86 6.3.4 Comparison to Wever and Lawrence ................. 90 6.3.5 Comments on the Bekesy result .................... 94 6 95 7 Summary Appendices A Summary of experimental animals and calibrations 97 A.1 Brief description of each experiment ......... . 97 A.2 Acoustic crosstalk for each animal .......... . 102 A.3 Changes in microphone calibration .......... . . . .. . . . . 110 A.4 Noisefloor calculations. ............ 123 A.5 Effects of TTX. ............ 130 B Summary of results: Stimulus to one window 139 C Summary of results: Stimuli to both windows 175 Bibliography 227 7 ... 8 Chapter 1 Introduction 1.1 Ossicular versus non-ossicular coupling The auditory portion of the fluid-filledinner ear (the cochlea) is enclosed by a bony capsule with two membrane-covered holes that face the middle-ear air space: the oval and round windows. In a normal ear sound is transmitted from the tympanic membrane (ear drum) to the oval window of the cochlea by the ossicles (malleus, incus, and stapes) (Fig. 1-1A). The tympanic membrane and ossicular system act to increase the soundpressure level between the ear canal and the cochlea. This increase is generally presumed to be a result of the large area ratio between the tympanic membrane and the stapes footplate (Pickles, 1988). The round window acts as an outlet that releases the pressure transferred to the oval windowby the ossicular motion. In pathological human ears with the ossicles missing hearing sensitivity is greatly reduced but hearing is still possible. In this case the sound pressure in the ear canal is neither magnified nor transmitted selectively to the oval window of the cochlea; instead the ear canal sound-pressure wave acts approximately equally on both the oval and round windows (Fig. l-lB). 9 MALLEUS L OW RANE W WNE LEA -A EAR C EAR C r I TYMPI CAVI B A Figure 1-1: A: Schematic of a normal human ear. A sound pressure at the tympanic membrane, PT, is magnified and transmitted to the oval window of the cochlea through the ossicular system (malleus, incus, and stapes). B: Schematic of a human ear missing the tympanic membrane, malleus, and incus. PT is not magnified and acts approximately equally on both the oval and round windows. Peake et al. (1992) developed a model that predicts hearing levels in both cat and human when the tympanic membrane, malleus, and incus are missing. They suggest that an important mechanism for hearing in such pathological cases is direct coupling of sound to the cochlear windows and that the cochlea responds to the pressure difference between the oval and round windows. Approximate agreement between model predictions and hearing levels in pathological ears supports the conclusion "For ears in which the tympanic membrane-ossicular chain mechanism has been disrupted available evidence for cat and human is consistent with the hypothesis that the sound-pressure differenceat the cochlear windowsis the dominant stimulus mechanism, at least for the higher frequencies (i.e. above 0.8 kHz)" (Peake et al. p. 258). It is difficult to come to a conclusion about the Peake et al. model fit to experimental data at lower frequencies because there are few experimental data. The existing data are discussed in Chapter 1.3. 10 1.2 The pressure-difference assumption The pressure difference between the oval and round windows is often assumed to be the only acoustic stimulus to the cochlea. This assumption is prevalent in both basic science and clinical explanations of cochlear function. Models of the inner and middle ear usually assume that the cochlear fluid is incompressible and that the response of the cochlea is proportional only to the pressure difference between the oval and round windows (e.g. Zwislocki, 1965; Allen, 1985; Peake et al., 1992). Surgical approaches to hearing improvement in ears without tympanic membrane, malleus and incus attempt to maximize the window pressure difference (e.g. Wullstein, 1956; Peake et al., 1992; Merchant et al., 1995; Rosowski et al., 1995). For example, in the type IV tympanoplasty procedure the surgeon places a facia or cartilage graft across the middle-ear air space to act as a shield that isolates the round window from sound pressure in the ear canal; it is assumed that the graft functions to increase the pressure difference between the oval and round windows and thus improve hearing. The best surgical results yield hearing losses of about 20 dB. However, the surgical results are extremely variable; only 50% of the surgeries yield hearing losses of 30 dB or smaller, and post-surgical hearing losses of 40 - 50 dB are not uncommon (Wullstein, 1956; Lee and Schuknecht, 1971; GotayRodriquez and Schuknecht, 1977). If the cochlea is assumed to be a linear system the pressure-difference assumption can be expressed as Cochlear Response = D(Pow- PRW) (1.1) where D is a complex constant and Pow and PRW are the complex amplitudes of the sinusoidal sound pressures at the oval and round windows (Fig.1-2). If Equation 1.1 holds 11 "C··lil··"sDXIILI······LIIID'i·l·l·i and the cochlear system is also reciprocal then a volume velocity at the oval window, Uow, produces a volumevelocity at the round window,URW, such that Uow = -URW. 1 Acous shield betwe oval and round windo Figure 1-2: A schematic showing Pow and PRW, the pressures at the oval and round windows, respectively. Uow and URW refer to the volume velocities at the oval and round windows. It is commonly assumed that Uow = -URw. 1.3 Experimental results relevantto the pressure-difference assumption There is little experimental support for the pressure-difference assumption expressed by Equation 1.1. In fact, it has been suggested that the cochlea responds even when the lIf the cochlea is a linear, reciprocal system and if the response for all Pow and PRW is proportional to (Pow - PRW), then Uow = -URW. Proof: Use a linear two-port network to represent the pressures and volume velocities at the oval and round windows. Uow = Y11 Pow + Y12 PRW (1.2) (1.3) It is assumed that the response of the system, here the volume velocity,is proportional to the difference URW = Y21 Pow + Y22 PRW in pressure between the two windows. Uow = Y11POW + Y12PRW = a (POW - PRW) (1.4) URW = Y21 POW + Y 22 PRW = b (POW - PRw) (1.5) Equation 1.4 shows that Y11 = -Y12 = a, and Equation 1.5 shows that Y21 = -Y 2 2 = b. Reciprocity requires that Y21 = Y12 which sets a = -b. Since a = -b, Equations 1.4 and 1.5 show that Uow = -URw. 12 co . 20.. 40 6 0 -: ...... I ..: 2 4 0.01 2 4 0.1 2 4 1 Frequency (kHz) Figure 1-3: Result taken from B:k:sy (1936a; 1960, Fig. 5-10). Mean hearing thresholds from five cases with unilateral loss of the eardrum, malleus, and incus" (B6ksy, 1960). Hearing levels indicate hearing thresholds in dB relative to the mean hearing threshold on the normal side on which an "otological examination had shown that the inner ear was normal" (Bksy, 1960); a hearing level of 40 dB corresponds to a hearing loss of 40 dB. The results shown here suggest that hearing improves as frequency decreases for ears missing the tympanic membrane, malleus, and incus. pressure difference between the oval and round window is zero. Bk6sy (1936a) reported average hearing levels from five patients with unilateral missing tympanic membranes and ossicles. He assumed that their cochleas were normal since the patients had normal hearing on the nonpathological side. Bk6sy concluded that the results shown in Fig. 13 appear to be inconsistent with Equation 1.1 through the following argument. At low frequencies the wavelength of sound is much greater than the distance between the oval and round windows (and the dimensions of the middle-ear cavity). Thus, at low frequencies the spatial variation in pressure between the oval and round windows is expected to be small and the pressure difference between the oval and round windows should decrease as frequency decreases. As a result the pressure-difference assumption expressed by Equation 1.1 predicts that hearing sensitivity in ears with no tympanic membrane, malleus, and incus should decrease as the frequency lowers. Instead Fig. 1-3 reports an improvement in hearing as frequency (and presumably pressure difference) 13 Uc -1---".---"1111----___ · decreases. Based on the results shown in Fig. 1-3 Bk4sy hypothesized that the cochlea may appear to be compressibledue to fluid flowthrough the endolymphatic and perilymphatic ducts or compressibility of cochlear blood vessels. Shera and Zweig (1992) developed a model in which the scala media is assumed to be compressible; they conclude that such a model matches the Bekesy result shown in Fig. 1-3. Other evidence has some consistencies with the pressure-difference assumption expressed by Equation 1.1. Wever, Lawrence and Smith (1948) showed in cat that sound applied to the cochlea at the round window produces a cochlear-potential magnitude similar to that produced by the same sound applied to the oval window (the angle of the cochlear potential was not reported). Wever and Lawrence (1950) applied tonal stimuli to the oval and round windows simultaneously and measured the cochlear-potential response. (The oval-window stimulus was applied at the tympanic membrane through the ossicular chain whilethe round-windowstimulus was applied through a tube coupled directly to the round-window membrane.) The stimuli were balanced such that each of them produced the same cochlear-potential magnitude when applied alone. Wever and Lawrence (1950, p. 462) described the response when the two stimuli were presented simultaneously and the angle between them was varied over one cycle: "the cochlear potentials vary in magnitude according to the phase relation between the sound waves entering by the two pathways. Under usual conditions a phase relation can always be found at which this response is just double what it would be for either pathway alone. This is a maximum value for these stimuli; the response falls off if the phase is altered in either direction from this setting. As the phase is further altered the response falls rapidly, and it approaches a value of zero as the phase is changed 180 degrees from the 14 maximum setting". Fig. 1-4 shows the only example of such a measurement that was published by Wever and Lawrence (1950). 20 ._ 4-' 0 10 CL a) _r 0. 0 O -90 0 90 180 270 PHASE - DEGREES (arbitraryreference) Figure 1-4: Result taken from Wever and Lawrence (1950). The cochlear-potential magnitude was measured as the oval and round windows were simultaneously stimulated. The phase of one of the stimuli was varied. This plot shows the cochlear-potential magnitude as a function of the phase of the varied stimulus. The value 0 degrees was arbitrarily chosen and does not mean that the two stimuli had a phase difference of 0 degrees at that point on the axis. In another set of experiments, stimuli balanced as described above were delivered directly to the oval and round windows and the angle between the stimuli required for a minimal magnitude response, ,bMIN, Was plotted as a function of frequency. The result is shown in Fig. 1-5. At frequencies below 1000 Hz and above 4000 Hz the data in Fig. 15 are clearly inconsistent with Equation 1.1. Even though IPowl and PRwI are not known, Equation 1.1 requires the difference in angle between Pow and PRW to be zero when the cochlear-response magnitude is a minimum. The angle differences reported in Fig. 1-5 range from 0.03 to 0.09 cycles (11 to 34 degrees) for frequencies below 1000 Hz while at frequencies above 4000 Hz the angle differences range from 0 to 0.5 cycles (0 to 15 0.5 180 0.4 C, , 0.3 z 0.2 135 - z 90 a (D (a 45 0.1 CD CD 0.0 102 103 10 Frequency (Hz) Figure 1-5: Result taken from Wever and Lawrence (1950). The oval and round windows were stimulated simultaneously and the phase relation between the stimuli was varied until a minimum cochlear-potential response was obtained. The phase difference between the oval and round-window stimuli required for this minimal cochlear-potential response, bMIN, is plotted here as a function of frequency. 180 degrees). At frequencies between 1000 Hz and 4000 Hz the data shown in Fig. 1-5 are consistent with Equation 1.1 because the differences in angle between Pow and PRW are nearly zero. However,it is impossible to relate directly the data in either Fig. 1-4 or Fig. 1-5 to Equation 1.1 because IPowl and IPRWI were not measured. 1.4 Common-mode and difference-mode responses A general linear system description of the cochlear response includes a "common-mode" term. In the cochlea common-mode mechanisms might include effects of cochlear fluid or blood vessel compressibility and flow through cochlear ducts. However, compressibility of cochlear contents need not produce a common-mode response; a symmetrically compressible cochlea may have no common-mode response. Common-mode mechanisms can be included in Equation 1.1 by adding a common16 mode term to the difference-modeterm. CochlearResponse = .~ ~'- ~ difference-mode response (Pow - PRW) + 1 C(POW + PRW) (1.6) common-mode response The gain constants D and C are the difference-modegain and the common-modegain, respectively. Equation 1.6 reduces to Equation 1.1 when C = 0. The aim of this thesis is to determine the relative importance of the difference-mode and common-mode terms to the cochlear response. The cochlear response to direct simultaneous stimulation of the oval and round windowsis examined in a manner similar to that of Wever and Lawrence (1950). The cochlear-potential response is measured in cat ears while the magnitudes and angles of the sound-pressure amplitudes at the oval and round windows are controlled; these cochlear-potential measurements are used to estimate the difference-modegain D and the common-modegain C. Comparison of D and C determines the importance of the pressure differenceat the two windows relative to the summation of pressure at the two windows. D and C are compared using the common-mode rejection ratio (CMRR). CMRR = 20logiolj _( 17 (1.7) 18 Chapter 2 Experimental methods 2.1 Subjects Measurements were made on seven cat ears. The first three ears were used to develop the experimental methodology; the pressure measurements in these animals were not stable to within less than a few dB over long periods of time. Appendix A contains a description of the measurements on each cat. 2.2 Stimulus paradigms Two types of stimuli were used: "single-sided" and "simultaneous". The single-sided level series are measurements of the cochlear potential, Vcp, made while either the oval or round window was stimulated with a tone of increasing sound-pressure level. The simultaneous-stimuli measurements refer to cochlear-potential measurements made while the oval and round windows were stimulated simultaneously; sound pressures of nearly equal magnitude (generally within 0.1 dB) were presented to the oval and round windows (Pow and PRW) while the angle of one of the pressures was varied over one 19 cycle. Vp was measured as a function of b, the phase difference between the sound pressures at the two windows. A measurement "set" refers to the set of data points collected as b varied from 0 to 1 cycle. 2.3 Experimental configuration Fig. 2-1 shows a schematic of the experimental set-up. The tympanic membrane, malleus, and incus were surgically removed from a Dial and sodium pentobarbital anesthetized cat. A petroleum-jelly soaked piece of cotton was inserted into the foramen of the septum so that the tympanic and bulla air spaces were isolated from each other. A calibrated probe-tube microphone and sound-source assembly positioned in the ear canal both delivered and measured the sound pressure in the space around the oval window, Pow. A similar assembly positioned over a hole made in the bulla wall delivered and measured the sound pressure in the space around the round window, PRW. The sound sources were "Beyer dynamic " earphones and the microphones were "Larson Davis 2530" quarter inch condenser microphones. 2.4 Probe-tube microphone calibration The experimental measurements required two calibrated microphones. OWmic refers to the probe-tube microphone which measured the sound pressure in the tympanic cavity and RWmic refers to the probe-tube microphone which measured the sound pressure in the bulla cavity. OWmic and RWmic were calibrated separately using a coupler and reference microphone, REFmic. A calibration source (Larson Davis) of 114 dB SPL at 250 Hz was coupled to REFmiC 20 MICROPHONE OV SOl STAPES PM MI . ROUND WINDOW MEMBRANE TYMPANIC CAVITY 7 BONY SEPTUM BULLA CAVITY MICROPHONE ) WINDOW )-SOURCE AND ]E-TUBE OPHONE a Figure 2-1: A schematic of the experimental set-up of the cat middle-ear. The inset is a blowup of the petroleum-jelly soaked cotton plug in the foramen of the septum. 21 to determine the relationship between sound-pressure level and the voltage output of REFmic. This measurement combined with a measurement of the frequency response of REFmic provided the transfer function between sound-pressure level, SPL, and the reference microphone voltage, VREFmic VFP ic One at a time, each probe-tube microphone and sound-source assembly was coupled to REFmic for the calibration procedure (Fig. 2-2). To calibrate the oval-window probe microphone, the transfer function between the voltage measured by the reference microphone, VREFmicand the voltage into the earphone generated by channel A of the was measured: VF-. digital-to-analog converter, VDACOW, 'W, Next the transfer function VDACO W between the voltage measured by the oval-window probe-tube microphone, Vowmic, and VDACow was measured: VOWMc These transfer functions yield the relation between VDACow was measured: VDACOW' sound-pressure level and the voltage of the oval-window microphone. SPL VREFi. VREFmic 1 [VDACow VOW VDACow i = SPL (2.1) VOWmic The transfer function between VRWmic SPL was found in the same manner. The roundwindow earphone was driven by channel B of the digital-to-analog converter VDACRW. The two microphones, OWmic and RWmi,, should measure the same sound-pressure level because they were calibrated with a common reference microphone. The relative calibration between the oval and round window microphones was checked periodically during the experiments on Cats #5, #6, and #7. After each calibration a short brass tube was used to couple the two probe-tube microphone and sound-source assemblies together; the two probe-tube tips were less than 2 mm apart. A sound common to both microphones was produced and it was confirmed that the calibrations of the two 22 To REFmic Amplifier A-- REFmic J (Larson Davis 2530) Brass Couplin Asseml Davis 2530) To OWmic Amplifier From Beyer Dynamic Earphone DACow Figure 2-2: The Beyer dynamic earphone is coupled to both REFmic and OWmicfor the calibration procedure of the oval-window probe-microphone and sound-source assembly. Experimental measurements were made with the same assembly,without REFmic. The part of the assembly to which REFmic coupled here is where the assembly was attached to the cat. A similar assembly is used to couple REF,mi and RWmic for the calibration procedure of the round-window probe-microphone and sound-source assembly. microphones were consistent. The results of this procedure are further discussed in Chapter 4. 2.5 Animal preparation Cats weighing between 1.7 and 2.2 kg were anesthetized with Dial (between 1.25 cc and 1.65 cc) and sodium pentobarbital (between 0.83 cc and I cc); the doses depended on the weight of the animal. Boosters of Dial (10% of the original dose) were given throughout the experiments, as determined by a toe-pinch response or 20% increase in heart rate. Most cats received 0.1 cc penicillin to fight infections. Removal of the ossicles required several steps. First, as much as possible of the cartilaginous ear canal was surgically removed in order to increase visibility of the middle23 ear air space. Next, an approximately circular hole with a diameter of about 5 mm was made in the dorsal-lateral-posterior part of the widely exposed bulla in order to provide visibility of both the round window and the foramen of the bony septum; this hole was later used to couple the round-window probe-tube microphone and sound-source assembly to the bulla cavity. Two methods were used to remove the ossicles; both required a dissecting microscope. The ossicles of Cats #1, #2, #3, and #4 were removed as follows. 1. The tympanic membrane was removed with a set of small forceps. 2. The manubrium was held with the forceps and gently wiggled until the lateral process and sometimes other parts of the malleus came loose; the pieces were removed. This made the incudo-stapedial joint partially visible. 3. The incudo-stapedial joint was disarticulated with the use of a "Schuknecht hook" (Storz Instrument Co.), and the incus was either removed or left loose in the tympanic space. 4. The foramen was plugged with petroleum-jelly soaked cotton by placing the cotton in the foramen with an approach through the ear canal and tympanic cavity. This approach was difficult due to poor visibility of the foramen through the earcanal. A different approach was used to remove the ossicles from Cats #5, #6, and #7. 1. The tympanic cavity was visualized through the 5 mm diameter hole in the bulla wall and the foramen. Either part of Spence's cartilage or the chorda tympani branch of the facial nerve was immediately in sight through the foramen. This dis- rupted the view of the incudo-stapedial joint. Any such "soft tissue" obstructions were moved out of the way by breaking them with the Schuknecht hook. 2. The Schuknecht hook was introduced into the tympanic cavity through the bulla cavity and the foramen; the incudo-stapedial joint was disarticulated. The visibility during this procedure varied among cats. 3. The tympanic membrane and other ossicles were removed through the ear canal. 4. The stapes and incus disarticulation was visually confirmed, by looking through the ear canal. 5. The foramen was plugged with petroleum-jelly soaked cotton through the bulla cavity approach. 24 After the ossicles were removed, the round-window wire-electrode tip was positioned near (Cats #1 to #4) or on (Cats #5 to #7) the round-windowmembrane. The electrode was advanced through a small hole in the bulla cavity with a micro-manipulator; the process was visualized through the larger 5mm diameter bulla wall hole with a dissecting microscope. The wire electrode was glued to the bulla wall to minimize movement and seal the hole. 2.6 Computer measurements of sound pressure and cochlear potential The digital-to-analog converter on a computer generated a two second stimulus tone(s). The two second amplified microphone-output(s) and cochlear-potential voltage responses were measured using the computer's analog-to-digital converter that sampled each response on a different channel at 12 kHz. Each channel of the analog-to-digital converter output was divided into 50 segments, and each segment was an integer number of periods in duration. The segments were averaged and the magnitude and angle of the fundamental component of the average is reported as the cochlear-potential response. The averaged microphone voltages were converted into sound-pressure levels using the previously measured microphone calibrations. 2.7 Cochlear potentials and TTX The AC cochlear potential is composed of two dominant components: cochlear microphonic (CM) and compound action potential (CAP). CM refers to the response of the cochlear sensory hair cells and is believed to increase linearly with sound-pressure level 25 over a large stimulus range (Pickles, 1988). The nonlinear CAP is generated by the auditory nerve fibers. The cochlear-potential response is represented as a linear-system response to the two inputs Pow and PRW (Chapter 3). This model is not consistent with the nonlinear CAP component in the cochlear response. Tetrodotoxin (TTX) was used to eliminate the CAP in Cats #6 and #7. TTX pharmacologically blocks action potentials generated by voltage-gated sodium channels; others have used TTX to block the compound action potential of the auditory nerve (Kaplan et al. , 1983; Dolan et al. , 1989). Here 1 mg of TTX (Sigma Chem. Co.) was mixed with 1 ml of artificial perilymph; a 3.13 mM solution resulted. Eight l of this solution was dropped on the round-windowmembrane from where it diffused through the round window-membrane into the cochlea over a time course of a few hours. The cochlear-potential response to clicks and tone bursts was measured pre and post TTX administration to confirm that the CAP response was eliminated; these results are included in Appendix A. 2.8 Definition of noisefloor Noisefloors are defined as follows for measurements on Cats #5, #6, and #7: M cochlearpotential measurements were made with no stimulus. The noisefloor is defined as the mean of these M magnitude measurements plus two standard deviations (all in dB). In most cases (but not all) M = 11. Such noisefloor measurements were not made during the experiments on Cats #1, #2, #3, and #4. However,several measurements of Vcp in response to a 1000 Hz stimulus were made. The mean plus two standard deviations of the appropriate frequency component of these measurements (M > 11) were used as estimates of the noisefloor. For these four animals, the noisefloor at 1000 Hz is defined to 26 be the same as the noisefloor at 800 Hz. Tables of noisefloor measurements are included in Appendix A. 2.9 Independent control of oval and round window sound pressures The bony septum that divides the cat middle-ear air space provides some natural acous- tic isolation between the oval and round windows. The petroleum-jelly soaked cotton plug that was inserted into the foramen of the septum further isolated the sounds at the two windows. A measurement of the acoustic "crosstalk" between Pow and PRW from Cat #7 is shown in Fig. 2-3, and measurements from the other cats are included in Appendix A. Such measurements of sound isolation with the plug in place demonstrated that the isolation was generally greater than 40 dB between 75 Hz and 1000 Hz. This amount of isolation allows for control of Pow and PRW through the separate sound sources. Note that, since Pow and PRW are always measured, acoustic "crosstalk" between the oval and round window sound-pressure sources is accounted for in the analysis. 2.10 Frequency range Measurements were made at frequencies between 75 and 1000 Hz. This low frequency range was chosen because low frequency results from both Bkesy and Wever and Lawrence (Chapter 1) contradict the pressure-differenceassumption (Equation 1.1). It was not possible to make measurements at frequencies below 75 Hz because the sound sources did not generate enough pressure to produce measurable cochlear potentials at these frequencies. The measurements were limited to low frequencies (< 1000 Hz) so 27 _Ll________(__plI_______y I ____ OW SOURCE OFF OW SOURCE ON RW SOURCE OFF RW SOURCE ON 0 A\ u -20 - VOWmic/VDACow -20 -40 _ m m ·+ . 4--1- .............. -80 A iallli ll ''till- 00 . 2 . 4I ..6 1 00 - U) aD >O r,. IVRWmicNDACRw I ''I'll -60 -80 0.5 -40 ...... "O -60 _ -100 IVOWmNDACRw [ - ......... IVRW,,,c/VDACowI 1 1000 -100 2 4 ~~,-nzcl~~~~~~; I ' 100 VOwmic- ZVDAC ......... ZVRW c I 24 6 iI1 8 LVOWmc ......... ZVRW - ZVDACow 1000 22 I4I4 ZVDACR w ZVDACRw 0.5 Cn a, 0.0 0 0>I 0.0 -0.5 -0.5 100 1 000 Frequency (Hz) A.1 100 1000 Frequency (Hz) Figure 2-3: Measurements of acoustic crosstalk between the tympanic and bulla cavities from Cat #7. LEFT: Measurement of the transfer function between the oval-window microphone response Vowmic and the oval-window sound-source input VDACOW, and measurement of the transfer function between the round-window microphone response VRwmic and the oval-window sound-source input VDACow. The round-window sound-source was off. RIGHT: Measurement of the transfer function between the oval-window microphone response VowmiCand the round-window sound-source input VDACRW, and measurement of the transfer function between the round-window microphone response VRwmic and the round-window sound-source input VDACRW. The oval-window sound-source was off. 28 that it is reasonable to assume that the pressure at each probe-tube-microphone input is the same as the pressure at the respective cochlear window a few millimeters away. At these frequencies the wavelengths are much greater than the distance between the probe-tube and the window; the shortest wavelengths are more than 30X the largest cavity dimensions. The validity of this assumption was tested (Chapter 29 4.2). 30 Chapter 3 Methods of estimating common and difference-mode gains, C and D The cochlear potential measured at the round window, Vcp, is modeled as a linear function of the sound pressures at the oval and round windows, Pow and PRW. A linear system representation is shown in Fig. 3-1. Pow Linear System -0 Vcp PRW O- 4- Figure 3-1: A general linear system representation of the cochlear response Vcp to the pressures Pow and PRW. The system input is describe by acoustic variables, and the system output is described by electric variables. 31 Since Pow and PRW are two independent inputs, the response Vcp must also be described by two independent terms, as in Equation 1.6: D(Pow- PRW) + C(POW+PW) VCP 2 difference-mode response common-mode response . (3.1) The two independent terms of this equation include a "difference-mode" term, the prod- uct of the difference-modegain D and the difference-modeinput (Pow - PRW), and a "common-mode" term, the product of the common-modegain C and the common-mode input (Pow + PRW). The simultaneous-stimuli measurements of Vcp, Pow, and PRw (Chapter 2) are used and C, using two separate fitting to estimate the differenceand common-modegains, procedures of Equation 3.1 to the measured data (Chapter 3.1 and Chapter 3.2). All data points such that IVcpI > Noisefloor are weighted equally in the fitting procedures; data points below the noisefloor are not used. A model prediction for each data point, VcP, is calculated from the estimates D and C and the measured Pow and PRW for each measurement set. = D(Pow - PRW)+ 2 C(POW+ PRW) _cp The relative sizes of I (3.2) and ICI are described by the common-mode rejection-ratio (CMRR). D CMRR = 20logiol-Correlation coefficients that describe the fit of Vf/ (3.3) to the measured Vcp are calcu- lated for each measurement set (Chapter 3.3). Experimental and model parameters axe 32 Experimental and Model Parameters Symbol Description Pow PRW VCp PDIFF = POW - PRW PSUM = (POW + PRW) VcP Complex pressure at the oval window (N/m 2 ) Complex pressure at the round window (N/m 2 ) Complex voltage at the round window (cochlear potential) Difference-mode pressure Common-mode pressure Model prediction of cochlear potential Estimate of the difference-modegain (Volts !M') Estimate of the common-modegain (Volts -N-) Estimate of the common-mode rejection ratio D CMRR Table 3.1: Experimental and model parameters. summarized in Table 3.1. 3.1 Linear fit to the data A linear-least-squares fit of Equation 3.1 is made to the data points of each measurement set in the followingmanner. The notation in Equation 3.1 is simplified to express the model as VIp = DPDIFF + CPSUM (3.4) where PDIFF = POW-PRW and PSUM = (POW+PRW). Equation 3.4 can be expressed as VCpa= D PDIFF,+ C PsuM, (3.5) where the subscript i refers to a specific data point. Each measurement set consists of a series of N such data points and can be expressed in matrix format as VcP = Pp3 where 33 (3.6) /r vCp2 VCp = (3.7) VCPN -~ ~ / I Ic VrGP., J / P= rPDIFF PSUM1 PDIFF2 PSUM2 (3.8) PDIFFN PSUMN (f D (3.9) A) The estimate of /, ,, that minimizes the expression N X2 = i=l I(D-PDIFF +-CPSUM)-VCPij = IP'/-Vcp'I (3.10) is found using singular value decomposition (SVD) techniques to solve Equation 3.6 for p (Press et al. , 1992). This method is used to eliminate undesirable effects of singular or nearly singular matrices. The NX2 matrix P defined by Equation 3.8 can be expressed in terms of the product of three new matrices: P =U. W .VT (3.11) where U is an NX2 orthogonal matrix (UT U = 1), W is a 2X2 diagonal matrix, and V is a 2X2 orthogonal matrix (VT V = 1). The that minimizes X2 from Equation 3.10 can be expressed as /i _ =P-Vcp = = V [diag( 34 )] U T . Vp (3.12) where [diag( )] refers to the diagonal matrix comprised of the reciprocal of each ele- ment of the diagonal matrix W defined by Equation 3.11. The solution of Equation 3.12 can be equivalently written as =V= (3.13) where the subscript (i) refers to the vector which comprises the ith column of U and V and wi refers to the diagonal element W(i, i) (Press et al., 1992). 3.2 Logarithmic fit to the data All data points are equally weighted in the linear-least-squares fit described above (Chapter 3.1). However, the measurements of Vcp made while the oval and round windows were simultaneously stimulated with variations in the relative phases of the stimuli have a dynamic range of about 40 dB; equal weighting of data points puts an emphasis on the regions where Vcpl is largest. To increase sensitivity to the points where Vcp is small, estimates of D and C are found with a least-squares fit to log(Vcp) = log(D_PDIFF+ CPSUM), (3.14) which requires the minimization of N 2 x2= Ilog(b , PDIFF + PSUM)-(CP) -* (3.15) i=P Since Equation 3.15 is nonlinear it is not possible to use the method of Chapter 3.1. Instead, a four dimensional space is searched to find values of D[, ZD, Cj, and C that minimize X2 . The search procedure employs the "fmins" function in Matlab (Macintosh version 4.1, The Mathworks, Inc.) to find a local minimizer of Equation 3.15. The "fmins" function 35 uses a "simplex" method (Nash, 1979; Press et al., 1992) to search the four dimensional space. In this case the "simplex" is a four dimensional geometric shape which must contain the desired values of IJD, D, C, and LC. The values of D, D, CJ, and ZC that were found using the least-squares fit of Equation 3.4 are used as an initial guess to center the simplex. The four dimensional simplex is defined by five vertices which are determined using the nonzero initial guess; each element of each vertex is between 0.9 and 1.1 times the initial guess. Next, Equation 3.15 is evaluated at each vertex of the simplex. The vertex that produces the largest value when Equation 3.15 is evaluated is replaced; it is reflected about the centroid of the other three vertices and through steps of reflection, expansion, reduction, and contraction (Nash, 1979) the vertex with a maximum function value (Equation 3.15) is replaced. This process is repeated until the simplex has shrunk to a size such that the evaluation of Equation 3.15 at all vertices differs by less than 0.0001. The estimates of IDJ, LD, C, and ZC at this local minimum of Equation 3.15 are used as the "logarithmic" model fit. 3.3 Correlation coefficients Two correlation coefficients are computed for each measurement set; PMAG describes the model fit IfcpI to IVcpl, and pz describes the model fit ZLcp to LVcp. The difference between the variance of the measured magnitude and angle data, MAG 1 N N- 1 [Illog(cP - 2 lg(V)cp)11 (3.16) 1N - (3.17) 2 = N l E VCP-LVCP, and the variance of the mean squared error between the data and model prediction, 2 1 N aMAG-ERROR= N-2[Iollo(Vcp)1N - 2 i=l1 36 log(Vcp)I)] (3.18) 1 2 N VcP I-ERROR= N-2 i i=_ 2, - lVCp] (3.19) is used to calculate the correlation coefficients PMAG = M--AG- AG-ERROR oMAG (3.20) and a2 _ a2 P =-E L b-ERROR O (3.21) In order to compare the two model fits, linear (Chapter 3.1) and logarithmic (Chapter 3.2), the correlation coefficients for both models are based on Equation 3.14; additionally all data and model fits are plotted on logarithmic scales. Vcp and LVcp refer to the mean value of the measurement set and N is the total number of data points in the measurement set. IV'cpl and LVcp, refer to the model prediction at the ith data point. 37 __·1_··1_1____1___^_^___-·-___ 38 Chapter 4 Pressure measurement errors Categories of potential errors in the measurements of Pow and PRW include: errors in the calibration of the microphone systems and pressure variations within the tympanic and bulla cavities, which make the measured pressures differ from the pressures at the oval and round windows. This chapter discusses these errors and estimates their sizes. 4.1 Calibration errors 4.1.1 Stability of absolute and relative calibrations The exact calibration of each microphone is not critical for the experiments presented in this thesis. However, the relative calibrations of the two microphones used to measure Pow and PRW must be determined precisely. For example, if a common tone is presented identically to both microphones it is critical that the calibrated sound-pressure response be the same in magnitude and angle for both microphones. Changes in temperature and humidity may affect each absolute microphone calibration. However, such changes are likely to be correlated between the two microphones 39 and probably do not introduce significanterrors. The calibration procedure (discussed in Chapter 2.4) determines the ratio between the sound pressure at the microphoneinput and the voltage generated at the microphone output, i*. The calibration procedure was repeated several times during the experi- ments on Cats #4, #5 , #6, and #7 and the changes in Pi as a function of time are Vmic used as one measure of error that exists in the measurements of Pow and PRW. The changes in - for all the cats are included in Appendix A. The largest variations in v-c for Cats #4 to #7 occurred in Cat #7; these variations are presented here as an example. Changes in the magnitude and angle of inVm,(iinitial Pmic(initial calibration) as a function of time calibrationa are shown in Fig. 4-1 for the measurements made on Cat #7. The maximum change in calibration during the experiments is used as a "worst-case" estimate of the error that exists in any given calibration. This estimate is plotted as a function of frequency in Fig. 4-2. The error estimates are not constant with frequency and they are not the same for the four cats. The oval-window microphone was consistently more variable than the round-window microphone. The maximum change in calibration during the experiment on Cat #7 was nearly 0.8 dB in magnitude at 100 Hz and nearly 0.015 cycles in angle at 1000 Hz. The maximum calibration changes seen in Fig. 4-1 probably over-estimate errors in Pow and PRW. The relative calibration between the oval and round window microphones was further checked periodically during the experiments on Cats #5, #6, and #7. After each calibration a short brass tube was used to couple the two probe-tube microphone and sound-source assemblies together; the two probe-tube microphone tips were less than 2 mm apart so the inputs to the microphones would be identical. When the calibrated 40 A Magnitude A Angle from Original Calibration (cycles) from Original Calibration (dB) 0.4 0.005 1000 Hz 0.0 0.000 -0.005 20 30 40 0.4 20 30 40 20 30 40 20 30 40 0.000 300 Hz -0.002 0.0 20 30 40 0.004 0.4 0.002 100 Hz 0.000 0.0 20 30 40 Time (hours) Time (hours) Figure 4-1: The differences in between the initial calibration and subsequent calibrations during the experiment on Cat #7. Note expanded vertical scales. The first measurement of Emr. is used to normalize all succeeding measurements of AuP; magnitudes (in dB) and angles (in cycles) of the ratios are plotted. Time of day = 17 hours is the time of initial calibration. -j Maximum Phase Difference (cycles) Maximum Magnitude Difference (dB) A .J p id .6- .4.20O '· .015 p [ t RWI I I 400 800 .01 .005 400 Frequency (Hz) Frequency (Hz) Figure 4-2: The maximum changes in iment on Cat #7. as a function of frequency during the exper- 41 .r l~~s~~~,-arr~ o~ lssa _ arr~~~ 800 _ .- d _,-- microphone outputs differed by more than 0.1 dB in magnitude or 0.002 cycles in phase the microphones were re-calibrated and any measurements that relied on the faulty calibration were discarded. 4.1.2 Movement of acoustic assembly Additional measurements weremade in a brass tube to understand better the microphone variations that occur over time and that occur as a result of coupling and decoupling to and from the cat head. In the tube, as in the cat head, the response of each microphone contains two sources of variability: variation in the microphone response and variation in the sound-source output. The variability in the two microphone responses was quantified by making repeated measurements in the brass tube assembly. Changes in the source output should cause correlated changes in the output of both microphones. Changes in microphone sensitivity could also be correlated if they result from changes in temperature or absolute pressure. 50 consecutive measurements were made with a 1000 Hz tone stimulus while the two sound-source and microphone assemblies were coupled together; the time between the first and 50 th measurement was about 5 minutes. The sound pressure measured by the two microphones and the differences between the two microphone measurements are shown in Fig. 4-3A and C, respectively. Fig. 4-3A illustrates that the outputs of both microphones changed with time by about 0.15 dB in magnitude and 0.003 cycles in angle. The difference between the microphone outputs changed less with time; the variation was only 0.04 dB in magnitude and 0.0003 cycles in phase (Fig. 4-3C). These data can be interpreted to show that small changes occur in both sound-source output and microphone sensitivity over time, and the larger change is apparently in sound-source 42 output. Next, 50 consecutive measurements were made in which the two sound-source and microphone assemblies were uncoupled from and then recoupled to the brass tube between each measurement; the time between the first and 50th measurement was about 10 minutes. Such a procedure mimics the uncoupling and recoupling of the sound-source and microphone assemblies to the cat. The sound pressure measured by the two microphones and the differences between the two microphone measurements for this case are shown in Fig. 4-3B and C. The uncoupling-recoupling results (Fig. 4-3B) show changes in microphone output that have a range of about 0.3 dB in magnitude and 0.005 cycles in angle. The variation in the difference between the microphone outputs is about 0.1 dB in magnitude and 0.003 cycles in angle (Fig. 4-3C). The measurements in Fig. 4-3 indicate that the system is less stable when movements of the sound-source and microphone assemblies are made. The large correlation between the two microphone outputs clearly demonstrates that most of the observed variation is the sound-source output. The variations observed in the microphone outputs when movements of the brass-tube assembly are made are appreciably smaller than the total calibration variations in the cat ear observed when the system was recalibrated during the experiments (Fig. 4-1); the changes caused by movement of the system are likely to be a part of the total calibration changes (Fig. 4-1). 43 1 -11I1·-II--·--1II1111· ·Il·IUI·l·llll*LIII1II MAGNITUDE 1 4 (dB SPL) ANGLE (cycles) 0.296 -r- ,\ 1 U. - I' ------ .. . 0.295 Mic A ...... Mic B 110.2 -Mic 110.1 I.. †..... ! _. _ _ ! _ I l 50 25 0 p] 0.294 A Mic B 110.2- 25 0 I\ 5 50 4,\n U. JUU - Mic A ...... Mic B 110.1.,,.A . Mic B 110.0- 109.9- -Mi i .··- 1% a n A' 25 0 50 r 0 0.001 - - : .:~~ I i 25 50 |~~~~~~ Difference no recoupling ------Differencewith recoupling I V 0- 0.05 0.00 - . :4 0.290- -- Difference no recoupling ......Difference with recoupling U. IU' - 0.295 - ¥''~i. , I ,t -0.001 - 0 '?: X · ir '~~~~~jibv~~. -0.05 - -0.002 - I I I _I 25 50 0 25 Sample number .. ! 50 Sample number Figure 4-3: (A) 50 consecutive measurements by both microphones of a common 1000Hz tone within a tube. Here the system was not touched between measurements. The time between the first and 5 0 th measurement was about 5 minutes. (B) 50 consecutive measurements by both microphones of a common 1000 Hz tone within a tube. Here the system was decoupled and recoupled between each measurement. The time between the first and 5 0th measurement was about 10 minutes. (C) The difference between the measurements shown in (A) and the difference between the measurements shown in (B). This difference is a measure of the variation of the microphone responses. 44 4.2 Spatial variations in pressure in the tympanic and bulla cavities Pow and PRW are the measured pressures at the medial end of the ear canal and at the bulla wall. Differences may exist between these measured pressures and the pressures at the oval and round windows. To estimate these differences, pressure measurements were made at different locations in the bulla cavity (of a dead cat). The round-window sound-source and probe-tube microphone assembly was coupled to the bulla cavity as shown in Fig. 2-1. A second probe-tube microphone, mounted on a manipulator, was introduced into the bulla cavity near this assembly. This second probe-tube microphone was systematically moved across the bulla cavity from the bulla wall toward the round window, and the responses of both microphones to tonal stimuli were recorded. The calibration for the moving microphone was defined by assuming that the pressures measured by both microphones were the same when the moving microphone was positioned at the bulla wall. Fig. 4-4 shows the ratio of the two pressure measurements, as a function of distance from the movable probe tube entrance at the bulla wall, for measurements at 1000Hz. The 0 mm position defined the bulla wall position, and the opening of the round window niche was at the 4.6 mm position. A total of five measurements was made at each position during three trials; a trial consisted of calibrating the moving microphone by making a measurement while the probe tube was at the bulla wall and then making one to three pressure measurements at each location as the probe tube was advanced systematically toward the round window. These measurements and their averages are shown in Fig.4-4. The probe moving toward the round window measured slight variations 45 in the pressure magnitude relative to the round-window microphone; these variations were on average less than 0.05 dB different from the pressure magnitude at the bulla wall. There were also variations in the pressure angle relative to the round-window microphone output; advancing the moving microphone led to a lag or decrease in angle relative to the pressure at the bulla wall. On average, the angle at the round window niche lagged the angle at the bulla wall by about 0.0008 cycles; this lag is only 6% of the phase lag of 0.013 cycles predicted theoretically for unidirectional uniform plane wave propagation. 1 The presence of the probe-tube microphone in the bulla cavity had little or no effect on the pressure magnitude measured by the round-window microphone; while the measurements shown in Fig. 4-4 were made, the largest magnitude changes in the pressure at the bulla wall were less than 0.02dB in magnitude. The presence of the probe tube may have affected the pressure angle measured by the round-window microphone; the maximum change in these angle measurements was 0.001 cycles. However, such variations in angle measurement are smaller than the variations that result in movement of the acoustic system (Fig.4-3B). The measurements of Fig.4-4 support the assumption that there is little spatial variation in the pressure in the bulla cavity; therefore the pressure measured at the bulla cavity wall is an accurate representation of the pressure at the round window (Chapter 2.10). Pressure variations in the bulla cavity at 100 Hz were also measured; these variations were smaller than those shown in Fig. 4-4 at 1000 Hz. The differences between the pressure at the round window and the estimated PRW should be largest at 1000 Hz since the shortest wavelength involved in all experiments is at 1000 Hz. Additionally 'If the speed of sound is 345- and the distance traveled is 4.6 mm then the phase lag for a uniform plane wave would be o.o46m =0.013 cycles. 1000 sec - -1 46 the differences between the measured pressure and the actual pressure at the oval or round window should be greatest in the bulla cavity since this cavity is larger than the tympanic cavity. IPPROBE / 1PR I PPROBE -PW 0.0004 8 0.10- o o Individualmeasurements 0.00.0000 -00 Ag o o -0.00 o -0.0008 -0.10- -0.10 0 1 2 3 4 5 - o Individualmeasurements Average 0 1 2 3 4 5 Distance (mm) Distance (mm) Figure 4-4: The reported pressures are measured as a function of distance from the bulla wall and are relative to the pressures measured simultaneously at the bulla wall. A probe tube microphone was advanced from the bulla wall (Distance=0 mm) to the round window niche (Distance=4.6 mm) . 4.3 Summary of pressure error estimates Changes in the calibrations of the acoustic systems over the course of an experiment are the largest errors discussed here (Fig. 4-1). The contribution to these errors caused by movements of the system are clearly smaller than the total errors (Fig. 4-3). Errors due to spatial variation in pressure within the cavities are negligible compared to the total errors. The total errors observed for the measurements on Cats #1, #2, #3 were much greater than those observed for the measurements on Cats #4, #5, #6, and #7 (Appendix A). The measurement system was improved by altering the components of the sound-source and microphone assemblies to have tighter fits. For this reason the results 47 and discussion presented in the body of this thesis emphasize results from Cats #4 to #7; results from Cats #1 to #3 are similar and can be found in the appendices. 48 Chapter 5 Results: Stimulus to one window 5.1 Experimental results Single-sided cochlear-potential measurements were made as a function of increasing sound-pressure level while either the oval or round window was stimulated. The pressure at the unstimulated window was effectively zero because the foramen plug was in place. Examples of such measurements made on Cat #6 at 100 Hz, 300 Hz, and 1000 Hz are shown in Fig. 5-1, 5-2, and 5-3. These results are characteristic of results from all other cats (Appendix B). The cochlear-potential response is described by its magnitude and angle. A linear dependence requires: 1. The cochlear-potential magnitude must increase with stimulus level with a slope of 1 with dB scales. 2. The cochlear-potential angle must be independent of stimulus level. Nonlinear features can be seen in the pre-TTX measurements shown in Fig. 5-1, 5-2, and 5-3. The cochlear-potential magnitude does not always increase linearly with a slope of 1, even at levels well above the noisefloor; Fig. 5-3 provides the clearest example of 49 *r___UIIII__II____I_·-··I·IYI·IIIUII - CAT #6 100 Hz .50 -80 .25 -100 W () a, 0to L m -120 - - 0 a. 0 0 N -. 25 -140 -160 40 4 -. 0r - 0 - 60 80 -.50 100 0 -41 60 80 -io Pre-TTX I i 40 60 80 120 - - Pre-TTX I I~ .00 Post-TX . Post-TTX I 100 co a. o .t 't I I' . .5 n i a- 40 120 . a. 100 120 zA; I i . I I I I I 40 60 80 I 1I I 100 120 LEVEL (dB SPL) LEVEL (dB SPL) Figure 5-1: CAT #6: 100 Hz. TOP: Magnitude and angle of Vcp as a function of sound-pressure level both before and after the application of TTX. Either the oval or round windowwas stimulated. BOTTOM: Ratio between the oval-windowresponse and the round-window response from the plots shown at the top. 50 CAT #6 300 Hz .50 -80 .25 -100 , 0) ar 0 a -120 0 0 0 N -140 -.25 -160 -.50 40 60 80 100 120 40 60 80 c, a) a, 4 -- -& .55 Pre-TTX Post-TTX - I O --. --- = , . A > ! i I-r' I , .A 40o 60 80 I 100 .45 - 120 120 Prp-TTX Post-TTX .5 .c) - -a :o - 1 . 100 > 40 3; i I .I I I I 60 80 100 I 120 LEVEL (dB SPL) LEVEL (dB SPL) Figure 5-2: CAT #6: 300 Hz. TOP: Magnitude and angle of Vcp as a function of sound-pressure level both before and after the application of TTX. Either the oval or round window was stimulated. BOTTOM: Ratio between the oval-window response and the round-window response from the plots shown at the top. 51 CAT #6 1000 Hz -80 -1 -·*.. -'*-O-A---- .25 OW Pre-TTX RW Pre-TTX OW Post-TTX RW Post-TTX noisefloor slope=1 0 00 a) 0 m a- -. 25 1- -120 > 0 C G. N -. 50 1 40 -. 75 -160 40 60 80 I I I 60 80 100 120 - Post-TTX ............. - a I -. -. Prm-TT .55bb . -. Pre-TX . 0 40 100 120 I -- 4 - ~I I Post-TX r .5 _-------~r, _f__--------- .> 1 o -4 - I I I, 40 60 80 I .45 I 100 120 > _I 40 LEVEL (dB SPL) I I I 80 I 120 LEVEL (dB SPL) Figure 5-3: CAT #6: 1000 Hz. TOP: Magnitude and angle of Vcp as a function of sound-pressure level both before and after the application of TTX. Either the oval or round window was stimulated. BOTTOM: Ratio between the oval-window response and the round-window response from the plots shown at the top. 52 this nonlinear feature. At the stimulus levels between 60 and 80 dB SPL the cochlear- potential magnitude both increases and decreases with increasing stimulus level. The cochlear-potential angle varies over the entire stimulus range; pre-TTX 100 and 300 Hz measurements (Fig. 5-1 and Fig. 5-2, pre-TTX) have cochlear-potential angles that increase with stimulus level over much of the stimulus dynamic range. (Many of the other 100 and 300 Hz measurements included in Appendix B have cochlear-potential angles that decrease with increasing stimulus level.) The cochlear-potential angle at 1000 Hz (Fig. 5-3) increases with increasing stimulus level except for a sudden quartercycle decrease at a mid-stimulus level. This type of transition is evident in all of the 1000 Hz measurements on the other six animals (Appendix B). TTX was added to the cochleas of Cat #6 and Cat #7 (Chapter 2.7) to reduce the nonlinear component of the cochlear-potential response. The effect of TTX on Cat #6 is shown in Fig. 5-1, 5-2, and 5-3, and the effect of TTX on Cat #7 is shown in Fig. B-7, B-16, and B-34. TTX had larger effects on the Cat #6 results compared to the Cat #7 results. The 1000 Hz cochlear-potential magnitude nonlinearity described above (Fig. 5-3) is essentially eliminated after the application of TTX. TTX also appears to reduce nonlinearities present in the cochlear-potential magnitude response at 100 and 300 Hz (Fig. 5-1 and 5-2). The ratio between the response to the oval-windowstimulus and the round-window stimulus is also plotted in Fig.5-1, 5-2, and 5-3 and in the Appendix B figures. In general, the cochlear-potential response magnitude is nearly independent of the stimulated window while the angle is nearly 0.5 cycles different for the two windows. The difference in magnitude (in dB) between the cochlear-potential response to the oval-window stimulus and the round-windowstimulus is often greater at lower stimulus levels than at higher 53 ^___II · _I___·___^___I________·____·_O___UIPI_ stimulus levels; however, the difference rarely exceeds 2 dB and is often less than 1 dB (Appendix B). The difference in angle between the cochlear-potential response to the oval-window stimulus and the round-window stimulus is usually 0.5 4 0.05 cycles; the largest deviations from 0.5 cycles occur most at the lower stimulus levels (Appendix B). Cochlear-potential magnitude sensitivities from all seven cats are compared in Fig. 54. These results are interpolated from the plots in Appendix B. The top plot shows the sound pressure required to produce a cochlear-potential magnitude of 10V when the stimulus is delivered to the oval window, and the middle plot shows the sound pressure required to produce a cochlear-potential magnitude of 10AuVwhen the stimulus is delivered to the round window. The bottom plot is the dB difference between the sound pressure required with an oval-window stimulus and the sound pressure required with a round-window stimulus to produce a 10lV cochlear-potential magnitude response; the difference is never more than 2.5 dB SPL. Cochlear-potential angle measurements from all seven cats are compared in Fig. 5-5. These results are also interpolated from the plots in Appendix B. The top plot shows the cochlear-potential angle, relative to Pow, which corresponds to a cochlear-potential magnitude of 101V when the stimulus is delivered to the oval window. The middle plot shows the cochlear-potential angle, relative to PRW, which corresponds to a cochlear- potential magnitude of 10V when the stimulus is delivered to the round window. The bottom plot is the difference between the two cochlear-potential angles. The difference is near 0.5 cycles in most cases and is always 0.5 ± 0.07 cycles. 54 IVCpl=10 gV 130 r- a a Stimulus to Oval Wind( OW 0 120 A 0a .J V -o0 0 110 V 'O 100 v o Wv V A o 0 V A 0f 8Kr o O A V 0 0 N X Cat #1 Cat #2 Cat #3 Cat #4 Cat #5 Cat #6 Pre-TTX Cat #6 Post-TTX Cat #7 Pre-TTX Cat #7 Post-TTX $ 90 _ __ I I ' 200 I I 600 800 ' 400 I ' 1000 Frequency (Hz) .dl _' l I;OU .J 03 CO co m 120 Stimulus to Round Window 0 a A a V V 110 -4 0 100 _ V A v V a o 0 V A & A a * o Cat#1 O Cat#2 A V O O b4 X Cat#3 Cat#4 Cat #5 Cat #6 Pre-TTX Cat #6 Post-TTX Cat #7 Pre-TTX Cat #7 Post-TTX O E A V 0 o N X Cat#1 Cat#2 Cat#3 Cat#4 Cat #5 Cat #6 Pre-lX Cat #6 Post-TTX Cat #7 Pre-TTX Cat #7 Post-TTX 4 90 I* I 200 200 ' 400 I I 600 800 . I 1000 Frequency (Hz) dB Difference 0 2 4 a_ Cn OW more sensitive 0 o aO ±1 0 V V V V a a] ....................... .. .......... ........... V A W A a A u a V -2 -A V V RW more sensitive III I ' ...... I , J I 200 400 ' . . . I i I I I ' I 600 800 1000 Frequency (Hz) Figure 5-4: TOP: Sound-pressure levels required for a 10upVcochlear-potential magnitude response when the oval window was stimulated. MIDDLE: Sound-pressure levels required for a 10LV cochlear-potential magnitude response when the round window was stimulated. BOTTOM: The dB difference between the top and middle plots. 55 '----- '--·----·---···1"*-`·I-r·r-r-·ll· - al- IVCpl=10 VV hl- U., r U) a) O Stimulus to Oval Window o Cat#1 A o .4 A v V 0.0 o V Q, 0 V V 6i \l V v A aP IS -0.5 I 200 I I ' 400 I 8 1000 600 800 1000 o o o m x Cat #2 Cat #3 Cat #4 Cat #5 Cat Cat Cat Cat #6 #6 #7 #7 Pre-TTX Post-TTX Pre-TTX Post-tTX Frequency (Hz) 1 .U _ Stimulus to Round Window a) co 0 9 o Cat#1 -A U) I 0.5 .= a. o Cat#2 VV a V 0 A Cat #3 v Cat#4 o v o * o m Cat #6 Pre-TTX Cat #6 Post-TTX Cat #7 Pre-TTX z Cat #7 Post-TTX v v \ 0.0 Cat #5 v - I I I I 200 400 600 800 ' I 1000 Frequency (Hz) 0.55 Difference Ao OW leads v 0.50 a, o(D 0 v V A OW lags v v 0.45 o Cat #1 o A v - Cat #2 Cat #3 Cat #4 Cat #5 o o m x Cat Cat Cat Cat #6 Pre-TTX #6 Post-TTX #7 Pre-TTX #7 Post-TTX V 0.40 200 400 600 800 1000 Frequency (Hz) Figure 5-5: TOP: Cochlear-potential angle when the cochlear-potential magnitude re- sponse was 10/tV and the oval window was stimulated (relative to angle of Pow). MIDDLE: Cochlear-potential angle when the cochlear-potential magnitude response was 10,uV and the round windowwas stimulated (relative to angle of PRW). BOTTOM: The difference between the top and middle plots 56 5.2 Discussion If the common-mode gain C is negligibly small in magnitude (pressure-difference assumption), when only the oval window is stimulated Vcp = DPow, since PRw (5.1) 0. Likewise, when only the round window is stimulated the pressure- difference assumption can be expressed as Vcp = -D PRW, since Pow (5.2) O. Equations 5.1 and 5.2 show that the pressure-difference assumption requires the cochlear-potential magnitude to be independent of the stimulated window and the cochlear-potential angle to be dependent on the stimulated window such that the difference between the cochlear-potential angles when the oval and round windows are stimulated is 0.5 cycles. = IDI IPowl JVcpI = ID IPRw (5.3) (5.4) Vcp = LD+ LPow /Vcp = ZD + LPRW+ 0.5 cycles (5.5) (5.6) Stimulus to oval window: Stimulus to round window: IVcpl and Stimulustooval window: Stimulus to round window: Fig. 5-4 and 5-5 show that these requirements of the pressure-difference assumption are approximated when IVcpt =. 10pV. Fig. 5-4 shows that the ratio between the ovalwindow and round-window sound pressures, when Vcpl = 101&V,is never greater than 2.5 dB and this ratio is often ±0.2 dB. Fig. 5-5 shows that the difference in cochlearpotential angle between the responses obtained from an oval-window and round-window stimulus is nearly 0.5 cycles. 57 Differences between the results shown in Fig. 5-4 and 5-5 and the pressure-difference assumption can be interpreted as a combination of measurements errors and contributions of the common-mode response. A general representation of the single-sided stimuli responses uses Equation 3.1 when the oval and round windows are stimulated, respectively. Stimulus to oval window: Vp = D Pow + 2C Pow (5.7) 1 Stimulus to roundwindow: Vcp = -D PRW + -C PRW (5.8) Equations 5.7 and 5.8 could be solved simultaneously to give estimates of D and C. However, the methods of the next chapter are more robust in the estimates of C. The single-sided measurements presented here do not control for small amounts of acoustic crosstalk through the foramen plug; instead the unstimulated window pressure is assumed zero. Additionally, the cochlear-potential measurements are taken at different times, not simultaneously, and small changes in cochlear sensitivity can occur and cause small changes in the measured cochlear-potential response. If ICI << D I we can ignore the common-mode component and estimate D based on the pressure-difference assumption and the single-sided stimuli measurements discussed in this chapter. Stimulus to oval window): D - Stimulus to roundwindow: = VCP P Pow Vcp PRW (5.9) (5.10) Estimates of D as a function of stimulus level are shown in Fig.5-6 for the single-sided measurements of Fig. 5-1, 5-2, and 5-3. Estimates of D as a function of stimulus level for all other single-sided measurements are included in Appendix B. These estimates of D can be used as a measure of the linearity of a single-sided cochlear-potential measurement; if the cochlear response is linear then both ID1 and ZD are independent of stimulus level. 58 Fig.5-6 showsthat the estimates of D are dependent on sound-pressure level;therefore Vc p is not linear. The variations in D are largest at the lower sound-pressure levels. The dependence of D on level at 1000 Hz is prominent in both magnitude and angle; this dependence is much reduced after the application of TTX. The level dependency at 300 Hz is small compared to those at 1000 Hz and 100 Hz and it too is reduced after the application of TTX. At 100 Hz, nonlinearities in Vcp are present both before and after the application of TTX; the level dependence of LVcp seems to be reduced after the application of TTX. Level dependencies in D shown in Appendix B are not consistent for one frequency across cats or for one cat at all frequencies. In several cases the estimate of DI varies by one to two orders of magnitude and the estimate of ZD varies by nearly 0.5 cycles as a function of sound-pressure level (Fig. B-3, B-4, B-6, B-9, B-10, B-29 and B-33, pre- TTX). In other cases the estimates of IDI and LD are nearly constant as a function of sound-pressure level (Fig. B-7, B-18, B-19, B-27, B-31 and B-33, post-TTX). The difference-mode gain D appears to be level dependent, at least in some cases. At 1000 Hz the nonlinearities may be a result of the CAP contribution to the cochlear potential since D becomes nearly independent of level after the application of TTX. But the source of nonlinearity at 100 Hz is not clear. It could be argued that the TTX was not as effective for the lower frequencies because the TTX did not permeate the entire cochlea; neurons with the ability to phase-lock to a 100 Hz tone extend further toward the apex of the cochlea than neurons with the ability to phase-lock to a 1000 Hz stimulus. It is possible that the lower frequency stimuli evoked responses from apical neurons whose CAP's were unaffected by the TTX. It is also possible that the more apical hair cells have a nonlinear response. 59 Br*r I~I--Il~l--r~---r ----- ~----- ~I ZD Estimate IDI Estimate 100 Hz 2 _ -5 10 ^'^ /~1 1'1. U I 'V I- 4 0U) I 2 Cs a) 0 -.5 0 -6 10 _ 100 Hz 4 *-- /LU UVV: 'OSt- I I A ZD RW: Post-TTX 2 - I I I I 60 80 100 120 -1 I 60 1I 80 I 100 120 0 I . Z v 10 4 0C0 2 2 7 10 80 80 60I 60 4 4 - o ~~ ' 2 -..IDI:OW Pre-TTX 10: l---RW Pre-TTX --. . IDi:OW Post-TTX IDI:RW Post-TTX I i i I I 60 80 100 120 i r,," ~~I ,-, c) a, OW: Pre-TTX RW: Pre-TTX OW: Post-TTX RW: Post-TTX * I 0 0 (L 10 ZD --- ZD ..o. ZD ZD *.. -1 -1000 Hz 2 300 Hz _ __1 120 120 100 100 -.5 0 IDI: OW Pre-TTX -..- IDI: RW Pre-TTX *.. IDI: RW Post-TTX IDI: RW Post-TTX -... 4 10 a) 300 Hz 6 0C 10 O 4 C) : E'a ---1nn' · · II II J · LI ,L ..z. D OW: Pre--TTX --- ZD RW: Pre- TTX . D OW: Posit-TTX ZD RW: Pos :-TTX .5 \.e 4 2 106 - 60 80 I I 100 120 -1 - I I I I I I I I 60 80 100 120 Level (dB SPL) Level (dB SPL) Figure 5-6: Estimates of D from the single-sided cochlear-potential measurements on Cat #6 both before and after the application of TTX. TOP: 100 Hz. MIDDLE: 300 Hz. BOTTOM: 1000 Hz. 60 Fig. 5-7 and 5-8 summarize the estimates of D found from measurements on all seven cats. The estimate of D is reported for the level at which the interpolated cochlearpotential magnitude was 10u/V. There are not large differences between the estimates of D found from the stimulus to the oval window and stimulus to the round window cases. Inter-frequency variations for one cat are larger than inter-cat variations for one frequency. In general, IDI increases with frequency and LD decreases with frequency. This result is further discussed in Chapter 6. 61 _UC__II___Unl__ll1__11 · UI IC ·-I · V-l----- I._- IVCpl=10 RV Stimulus to Oval Window I 1 0-5 9 0 4 (1 Nv 2 9 CI 1 0-6 v o 0 A 'Cat #3 v Cat #4 Cat #5 o Cat #6 Pre-TTX o Cat #6 Post-TTX 4 Cat #7 Pre-TTX X Cat #7 Post-TTX 0 o Cat#2 A V 0 V 4 -V -a 2 -a 7 a A 0 · 2 I · 200 · I r 400 I I I 600 800 Cat #1 I A [ 0 50 10 v I · I 1000 Frequency (Hz) Stimulus to Round Window 2 5 1 0cS 4 0.o Iv 2 0 ' 10 6 V a o [ A V o O 4 X A M 0 a 0 0 v a- Vo A 50 41 'V 0 13a Cat #1 Cat #2 Cat #3 Cat #4 Cat #5 Cat #6 Pre-TTX Cat #6 Post-TTX Cat #7 Pre-TTX Cat #7 Post-TTX A 10 . , ..... . , I I I 200 400 600 I . I I 800 1000 Frequency (Hz) 10 _m Difference 0 5 co VV 9 0 V o -5 -10x10 7 a 0 A V VV I I I 200 400 600 I I 800 A V 0 o o m X Cat #1 Cat #2 Cat #3 Cat #4 Cat #5 Cat #6 Pre-TTX Cat #6 Post-TTX Cat #7 Pre-TTX Cat #7 Post-TTX ' 1000 Frequency (Hz) Figure 5-7: Estimates of ]IDtfound from Equations 5.9 and 5.10 at a sound-pressure level such that IVcpl = 10rtiV. 62 IVCi=l10 gV ,\r U.53 Stimulus to Oval Window m A z CD 0 0.0 I V31 O v 211 V \l V v T A 0 -0.5 ·I ' . , 200 A U.0 a , . I ,.. I I I 400 600 800 Frequency (Hz) 1000 Stimulus to Round Window 7- o Cat#1 -A VV C3 0.0 V m 0 Mv g v V v ,q z a -0.5 _ O A V 0 o N X Cat#2 Cat#3 Cat#4 Cat #5 Cat #6 Pre-TTX Cat #6 Post-TTX Cat #7 Pre-TTX Cat #7 Post-TTX __ I I I 200 ' I I 400 600 800 Frequency (Hz) 0.05 C, C.) O Cat #1 O3 Cat #2 A Cat#3 V Cat #4 - Cat #5 o Cat #6 Pre-TTX o Cat #6 Post-TTX M Cat #7 Pre-TTX X Cat #7 Post-TTX 1000 Difference o Cat#1 O A V O o N x 0.00 6 $ 0 (9 v _v (3 -0.05 V vv v Cat #2 Cat#3 Cat#4 Cat #5 Cat #6 Pre-TrX Cat #6 Post-TTX Cat #7 Pre-TTX Cat #7 Post-TTX -0.10 I 200 I ' 400 I , 600 I i 800 1000 Frequency (Hz) Figure 5-8: Estimates of the angle of D found from Equations 5.9 and 5.10 at a sound-pressure level such that Vcpl =- 10y 63 4"IIII"~""~""""""UI"~"~~-11111 · liL-·~·~·I~·SIBII~·I -- LI- - 64 Chapter 6 Results: Stimuli to both windows 6.1 Experimental results Simultaneous-stimuli measurement sets were made by stimulating both the oval and round windows and varying the phase difference b between the two stimuli over one cycle. All such measurement sets are shown in Appendix C. The discussion in this chapter emphasizes measurements from Cats #4, #5, #6, and #7 because errors in the pressure measurements of Pow and PRW were smaller during these later experiments. Fig. 6-1 and 6-2 show simultaneous-stimuli measurement sets made at 1000 Hz on Cat #7 with sound-pressure level as a parameter; the data in Fig. 6-1 were taken before the application of TTX and the data in Fig. 6-2 were taken after the application of TTX. The cochlear-potential magnitude and angle measurements are plotted as a function of 'b, the phase difference between the oval and round-window sound pressures. The left- hand plot is the cochlear-potential magnitude, the middle plot is the cochlear-potential magnitude in the region around ,b 0, and the right-hand plot is the cochlear-potential angle. Data points where Vcpl > Noisefloor 65 ·i___lU__rr__UMUU_··--··--L·-··-*IUU are represented by open circles and data IVCPI (dB re 1V) IVcpI (dB re 1V) /Vcp (cycles) 0.5 -80 -80 o Data points -100 -100 _ -120 -120 Linear fit --- Logarithmicfit 0 -140 ......................... I 1I -0.5 I 1 1 1 1 I -140 ................... 1 1 1 1 I 0 ............................... r - - - - -0.01 0.5 .9. I 1 0 0.01 -0.5 -0.5 0 0.5 -80 _ -80 -100 - -100 A 0 -120 -120 -140 -140 0 0.5 yi (cycles) -0.5 I | I -0.5 5.. ................................ I -0.01 0 Vy (cycles) -. 0.01 -0.5 · . ° · ' ! I o 0 · i I 0.5 Vi (cycles) Figure 6-1: Simultaneous-stimuli measurement sets and model fits at 1000 Hz on Cat #7 before the application of TTX. 66 /Vcp (cycles) IVcpl (dB re 1V) IVcpl (dB re 1V) U. -80 _ -80 , m o Data points Noisy data points Linear fit - -- Logarithmicfit - -100 -100 -120 -120 _ 4, 0 10O0e_7 -140 -.... noisefloor... 'I i . -.. . . . -0.5 89dB SPL ....................... I . . . . - . - 0 -140 I 0.5 e,,,, . ... ......... ..... ............ l -0.5 I ,· -0.01 0 l -0.5 0.01 l l l L l : II l l 0 l I II l 0.5 0.5 -80 -80 _ -100 -100 I0 -120 -140 -120 1000_7 99 dB SPL ...................................... . . . . . . a , . . . . . . - . - . . 0 -0.5 -140 ..... . - 1.I "" 0.5 * -0.01 . I. """a 0 -0.5 "" -0.5 0.01 i 2 0 M 1-4 0 0.5 0.5 -80 -80 -100 -100 I- -120 -120 '"-0.5 0 'L -140 .............................................. I1 - -0.5 . . II II . 0 . . -140 0,0~1 " ..................................... l I ! , · ! -0.01 0.5 0 · , I 0.01 -0.5 0 0.5 0 0.5 0.5 -80 I -80 -100 -100 _- -120 -120 -140 -140 _ _ . 0 -. J -0.5 0 0.5 -0.01 I.I . .. 0 Nf (cycles) NY(cycles) ' I . 0.01 -0.5 -0.5 N(cycles) Figure 6-2: Simultaneous-stimuli measurement sets and model fits at 1000 Hz on Cat #7 after the application of TTX. 67 nirrzrr,,lmr·rrur*rXr*uglg·uqunr · ------ points where Vcp < Noise floor are represented by open ovals. Each plot has a label associated with it to identify the measurement order; for example the label "1000e_7" refers to the fifth measurement made on Cat #7 at 1000 Hz. The measurement sets are plotted in order of increasing stimulus level and not chronological order, and the sound-pressure level printed on the magnitude plot is the measured sound-pressure level of both IPowl and IPRwl. Several features of the measurement sets shown in Fig.6-1 and 6-2 are seen in all of the measurements shown in Appendix C. The cochlear-potential magnitude plots are roughly symmetric about Ob= 0. A magnitude minimum occurs at an inter-window stimulus phase differenceObMIN - Ocycles. A magnitude maximumoccurs near = 0.Scycles and is always close to the sum of the two cochlear-potential response magnitudes recorded when the oval and round windows are individually stimulated. The dynamic range of a given measurement set, the dB difference between the maximum and minimum cochlear-potential magnitude, is roughly 40 dB when IPowl z IPRwl. The dynamic range is sometimes limited by the noisefloor, especially when Powl and IPRwI are at lower values. In general, the cochlear-potential angle data points increase with increasing values of b0except for a sudden 0.5 cycle shift at p t 0. However, for some of the ears deviations from this pattern occur, especially at the lower frequencies, as illustrated in Fig. 6-3 with examples from five of the seven experimental animals. Between 'b = -0.5 and b = 0 the cochlear-potential angle increases with increasing Oiand shifts by about 0.5 cycles at b = 0. But between pb= 0 and b = 0.5 the cochlear-potential angle does not increase at the same rate as it increased between b = -0.5 and 0b= 0. In fact, the cochlearpotential angle remains roughly constant between ,b = 0 and 0b = 0.1 for the examples 68 _ = fs m U.O _ 0O = 75a_4, 124 dB SPLI 75b_4,120dB SPL U.D~~~~ IA I[ 03 z 0 0~ A -0.5 0 (D 0 0 N E ka a o A a -1.0 -0.5 - - - - - - - - i -0.5 0 0.5 I F.5 0.5 -0 .5 A1 300c_5, 10dBSPL 0 0.5 I A Post-TTX: 300d?, 121 dB SPLI i 1.0 Pre-TTX: 100b_7, 127 dB SPLI Post-TTX: 100d_7, 126 dB SPL iI L 1.0 I A A in co C,, A 0 A A A A __ 0.5 \ia. 0.5 A. AA AA N &AAAAAAAA I 0 . .- I . 0 I -0.5 0.5 0 0 ~ _ ~~_"._. 1 .U IJ L_ I -0.5 A A40 0.5 0 _ 400d_3, 114 dB SPL I & , co <D 0 A A A -0.5 0.5 a- F-^ JAA A 0 .AI ^A A LA N &AAA A& 'L A A 400a.2, 114 dB SPL -1.0 -0.5 T1 -0.5 . . . . I . . 0 r{ 0 . -0.5 0.5 , , |l 0 . I 0.5 v (cycles) yV (cycles) Figure 6-3: Cochlear-potential angle measurements as a function of b, the phase difference between the pressure at the oval and round windows. These measurements were selected to demonstrate an asymmetry around b = 0. The legends identify the frequency of the measurement, the measurement order on a given cat, and the cat on which the measurement was made. 69 "~""l~""~""-~"~~p"~~"~W~~~"U····-----_ I shown in Fig. 6-3. To test if this asymmetry about b = 0 is a result of the order in which the data points were collected, data points from Cat #5 were collected both in order of increasing b and in a random order; there was no appreciable difference in the shape of the curve. The asymmetry could also be a result of nonlinear behavior of the neural component of the cochlear potential. The example from Cat #7 at 100 Hz in Fig. 6-3 shows that TTX did not affect the asymmetry, but TTX did not have large effects on the single-sided cochlear potential measurements at 100 Hz on Cat #7 either (Fig. B-7). The cause or mechanism of the angle asymmetry is not known. There are not large differencesbetween the pre-TTX measurement sets and the postTTX measurement sets on either Cat #6 or Cat #7. The biggest differences occur at 1000 Hz; 1000 Hz pre and post-TTX measurement sets are compared in Fig. 6-4. Differ- ences between the pre and post-TTX measurement sets were expected to be most obvious around ~p= 0 because single-sided level series measurements showed that TTX had the biggest influence on Vcp at the lower stimulus levels or when VcPI < -120 dB re 1V (Fig. B-33 and B-34). The only pre-TTX simultaneous-stimuli measurement set at 1000 Hz on Cat #7 which includes data points such that IVcp < -120 dB re 1V is shown in Fig. 6-1 and is labeled "1000b_7". Comparison of this pre-TTX measurement with the post-TTX measurement set in Fig. 6-2 labeled "1000d_7" shows nearly equivalent results in the region around ~p= 0, the region where the TTX was expected to have the biggest effect on the result (Fig. 6-4). Instead, the biggest difference between the pre and post-TTX measurements is an approximate 5 dB decrease in cochlear-potential magnitude after the application of TTX; this decrease is most easily seen in regions where 4p; 0.5 and in the single-sided measurements of Fig. B-34. Fig. 6-4 also compares the pre and post-TTX simultaneous-stimuli measurements from Cat 70 6 at 1000 Hz; A a000000 IVcpI (dB re 1V) (cycles) ZVcp 0.5 -80 _ [00On- 100 A A 10 - L0&3 ooo· Lo 0 - 1 20 Ar -140 I noisefloor ...... Pre-TTX: 1000b_7 Post-TX : 1000d_7 Pre-TTX: 1000b_7 0 Post-TTX: 1000d_7 -0.5 ! 0 -C).5 ,13 ~~i~o°°° -D 130-Dj A ........................................... II 00.5 - - - - 0.5 -100 0 - - 0. 5 0 0.5 -120 .OO . 0 1aep O0r[ ] -140 - -0.5 -0.02 0.02 0 OQO I i ! I -0.02 -0.02 v (cycles) 0.02 0 m (cycles) LVcp (cycles) IVcpl (dB re 1V) 0.5 -80 I &6666666 3A -100 0 -120 Pre-TTX: 1000a_6 o Post-TTX: 1000c_6 A -140 -noisefloor ._ . . -0.5 -100 -140 . I . . . -0.5 -0.5 0.5 0.5 0 A . I 0.!5 0 0.5 a 0 0 0 -120 Pre-TTX: 1000a_6 o Post-TT(: 1000c_6 ................................. A 0 ... ................................ I .................. I -0.02 0 V -0.5 _ I 0.02 -0.02 (cycles) .d . -~~~~ 0 I 0.02 ,W (cycles) Figure 6-4: Comparison of pre and post-TTX cochlear-potential measurements as a function of 7b,the phase difference between the pressure at the oval and round windows, when the oval and round windows were stimulated with nearly equal sound-pressure levels. TOP: Cat #7 measurements at 99 dB SPL. BOTTOM: Cat #6 measurements at 104 dB SPL. 71 ~~LI~--I~IX II l~ l lr-I· II~U·-IC~·--··l· ·sl - ~ ------ there are slight differences in the cochlear-potential magnitude and angle around 0b= 0. These differences could be a result of the TTX, or differences between pre and post-TTX measurements could also be caused by slight changes or imbalances in IPowl and IPRwl. 6.2 Model fits to the data: Estimation of C and D We estimate the difference-mode and common-mode gains using the methods described in Chapter 3. The measured values of Vcp, Pow, and PRW at each and every data point are used to determine the estimates D and C that produce the least-squares difference to Equation 3.4 ("linear fit") or Equation 3.14 ("logarithmic fit") for each measurement set. The model fits to the cochlear-potential data, Vcp, obtained from Equation 3.4 and Equation 3.14 are included on the plots of the simultaneous-stimuli measurement sets in Appendix C and Fig. 6-1 and 6-2. There are not large differences between the results of the two fitting procedures; the discussion here will concentrate on the linear fit of Equation 3.4. Many general aspects of the model fits are consistent with the data: the magnitude maxima from both the fits and the data are nearly the same and both occur at b - 0.5, the magnitude minimum from both the fits and the cochlear-potential data all occur at b -_0, and the angles of both the models and the cochlear-potential data change rapidly by about 0.5 cycles at b b 0. Differencesbetween the linear and logarithmic fits are so small that in most cases the two plots are nearly indistinguishable. The major difference is illustrated in Fig. 6-1 (measurement "1000a_7") and Fig. 6-2 (measurement "1000f_7"). The largest deviation between the linear model fit and the cochlear-potential data occurs near = 0 because the magnitude of the cochlear potential is small in this region and large fractional differences are not weighted strongly in the linear-least-squares fit of 72 Equation 3.4. The logarithmic fit does a better job fitting Vcp to the data points near b = 0 but the fit near p = 0.5 is not as good as the linear model fit. The linear model predictions of D and C from Equation 3.4 are summarized in Fig.65 for all measurement sets on Cats #4 to #7. The estimates of IDI are more than an order of magnitude greater than the estimates of C, and the magnitudes of both gains increase by approximately an order of magnitude as frequency increases from 75 to 1000 Hz. The estimates of IDI have a smaller standard deviation than the estimates of CI on a logarithmic scale, and the estimates of LD have a much smaller standard deviation than the estimates of LC. The common-mode rejection-ratio (CMRR) is calculated for all measurement sets using Equation 3.3: CRR = 20logo- D . CRR values are shown in Fig. 6-6 and do not appear to be a function of frequency. The mean values of CMRR range from 27.5 dB (75 Hz) to 34.5 dB (800 Hz). The lowest CIMRR is 18.6 dB at 300 Hz and the highest CMRR is 53.8 dB at 100 Hz. The variation in CMRR is not surprising since the standard deviation of C is large and CMiRR is calculated from C. The correlation coefficients calculated for the model fit to each measurement set using Equations 3.20 and 3.21 are shown in Fig. 6-7. In general, the magnitude correlation coefficients are higher than the angle correlation coefficients. With the exception of the two measurement sets at 75 Hz, the mean magnitude correlation coefficients are all greater than 0.95, and the mean minus the standard deviation of all magnitude correlation coefficients is greater than 0.9. The mean angle correlation coefficients are all greater than 0.85, and the mean minus the standard deviation of all angle correlation coefficients is greater than 0.7 (with the exception of the two measurement sets at 75 Hz). The angle correlation coefficients are more difficult to describe and less meaningful 73 -vA o o o 10 Mean and std of IDI (shifted -20 Hz) Cat #4 IDi (shifted -10 Hz) Cat #5 IDI (shifted 0 Hz) Cat #6 IDI (shifted 10 Hz) Cat #7 IDI (shifted 20 Hz) co 0 1 06 -- Mean and std of ICI (shifted -20 Hz) Cat #4 ICI (shifted -10Hz) * Cat #5 ICI (shifted OHz) * Cat #6 ICI (shifted 10Hz) * Cat #7 ICI (shifted 20Hz) A cr (I, 10 7 o CO 1 0 '8 I i I _I - 0 ~~~ ~ ~ . 200 400 . ii ii - ' 0 I I 600 800 1000 1.5 to 0 -0 1.0 0.5 I -w* * * * r N Mean and std C (shifted -20 Hz) Cat #4 ZC (shifted -10 Hz) Cat #5 C (shifted 0 Hz) Cat #6 C (shifted 10 Hz) Cat #7 ZC (shifted 20 Hz) 0 -0.5 I I 0 * I I 200 . * I I I 400 600 . ' I I 800 . I I -v-Mean and std D (shifted -20 Hz) A Cat #4 D (shifted -10 Hz) o Cat #5 D (shifted 0 Hz) o Cat #6 D (shifted 10 Hz) o Cat #7 ZD (shifted 20 Hz) 1000 Frequency (Hz) Figure 6-5: Estimate of D and C for each measurement set from Cats #4 to #7. D estimates are represented by open symbols and C estimates are represented by closed symbols. Because most of the measurements were at 100, 300, or 1000 Hz the plotted points tend to overlap. To increase legibility, points for a given cat are shifted right or left by a small amount, as indicated in the keys. TOP: Magnitudes of D and C. BOTTOM: Angles of D and C. 74 ju - A~ -V- Mean and std (shifted -20 Hz) A Cat#4 (shifted-10 Hz) o o o O O Cat #5 Cat #6 Cat #7 50 - I- (shifted 0 Hz) (shifted 10 Hz) (shifted 20 Hz) o o .- o 40- C. Do O 300] ,o 20- I- 13 o 0 0 10- l - II I I I I 0 200 400 600 800 1000 Frequency (Hz) Figure 6-6: Calculation of the common-moderejection-ratio (CMRR) from the estimates of D and C for each measurement set from Cats #4 to #7. Because most of the measurements were at 100, 300, or 1000 Hz the plotted points tend to overlap. To increase legibility, points for a given cat are shifted right or left by a small amount, as indicated in the keys. 75 3·ll---·-S · ll1llC-·1 - _ 1.0 r-' -7 AO ~ £0~ 0 o CD 0.8 A I. 0o 4qm 0Q Q- 0.6 _ -VA Mean and std (shifted -20 Hz) Cat #4 (shifted -10 Hz) o Cat #5 (shifted 0 Hz) O 0 Cat #6 (shifted 10 Hz) Cat #7 (shifted 20 Hz) 0.4 - II 1.0 400 200 0 I 600 800 1000 m 0 0.8 I--' N a- 0 0.6 03 I.A 0 O o Cat #5 (shifted 0 Hz) Cat #6 (shifted 10 Hz) Cat #7 (shifted 20 Hz) 0.4 a [] _ 0 0 .i. ii 200 400 600 800 1000 Frequency (Hz) Figure 6-7: Correlation coefficients calculated for each model fit from Cats #4 to #7. Because most of the measurements were at 100, 300, or 1000 Hz the plotted points tend to overlap. To increase legibility, points for a given cat are shifted right or left by a small amount, as indicated in the keys. 76 than the magnitude correlation coefficients because the angle data is periodic with a period of 1 cycle and the computed angle correlation coefficients can change when the angle data takes different values, or is "unwrapped" around different points. Fig. 6-8 compares the estimates of D found in Chapter 5 to those found here. The analysis in Chapter 5 assumes C = 0 and D is estimated as a function of level from the single-sided level-series measurements. The estimates plotted in Fig. 6-8 are the means computed from Cats #4 to #7 using the results of Fig. 5-7 and 5-8. Pre and post- TTX measurements for Cat #6 and #7 were made; only pre-TTX measurements are included in the mean estimates shown in Fig.6-8 so that the results from these cats don't dominate the results. Standard deviations are not included because each mean estimate from Chapter 5 is computed from only one to four data points. The simultaneous- stimuli measurement points in Fig. 6-8 are the mean values previously shown in Fig. 6-5. There do not appear to be large differencesbetween the two methods of estimating the difference-mode gain D. 6.3 6.3.1 Discussion General model behavior In the model described by Equation 3.1 Vcp depends on both the magnitudes and angles of the two complex constants D and C. This section illustrates how the model's behavior depends on these quantities; the magnitudes and anglesof D and C are specificallychosen and Response defined by Equation 6.1 is computed. The signals "waveA" and "waveB" are sinusoids of the same frequency and the variable Obdescribes the phase difference 77 -lll·--·-·IUIIIIIU··l _I_---- -- IL__ 10 5 co CO c() Q. O 10 n 0 200 400 600 800 1000 U.0 -V-- o- Mean ZD: Mean ZD: simultaneous stimuli single-sided stimuli o) 0 ,\ 0 -0.5 · 0 . ! I ! 200 ! ! ! 400 . !. I ! ! 600 I ! 800 . ! 1 1000 Frequency (Hz) Figure 6-8: Mean estimates of D using single-sided stimuli (Chapter 5) and simultaneous stimuli (Chapter 6). The single-sided mean values of D are computed from the data shown in Figures 5-7 and 5-8; only data from Cats #4 to #7 are used, and for Cats #6 and #7 only the pre-TTX single-sidedstimuli measurements are used. The simultaneous stimuli mean values of D were previously shown in Figure 6-5. 78 between them. Response = D(waveA - waveB) + IC(waveA + waveB) (6.1) Common-mode gain of zero A simple form of Equation 6.1 is to assume C = 0. Response = D(waveA - waveB) (6.2) Equation 6.2 is the pressure-difference assumption of Equation 1.1; three interesting cases of Equation 6.2 are illustrated in Fig. 6-9. 1. Fig. 6-9A shows the case of IwaveAl = waveBI and D = 1. Responsel goes to zero at bp= 0 and LResponse shifts from -0.25 cycles at = 0- to -0.75 cycles at ' = 0+. 2. Fig. 6-9B shows the case of IwaveAl = IwaveBI and D = j. IResponsel goes to zero at p = 0 and ZResponse shifts from 0 cycles at 4p= 0- to -0.5 cycles at 4p= O+ . 3. Fig. 6-9C shows the case of IwaveAl = 2waveBI and D = 1. Responsel goes to a nonzero minimum of IResponsel = IwaveA - waveBI at 4' = 0 and LResponse shifts from -0.25 cycles to 0.25 cycles near 4 = 0, but the phase shift is more gradual than the cases where IwaveAj = IwaveBI. To summarize, C = 0 requires Responsel to be a minimum at 4 = 0. This minimum is zero only when IwaveAl = IwaveBI. When IwaveAl = IwaveBI, Response is undefined at 4b= 0 because Responsel = 0. In general, ID affects IResponsej, and LD affects LResponse. Differences between the magnitudes of the two input waves, IwaveAl and IwaveB}, can have big effects on Responsel at values of b near zero; when these magnitudes are not equal it is impossible for Responsej to reach zero. To connect these examples to the experiments of this thesis, suppose that Pow = waveA, PRW = waveB, Vcp = Response, and the common-mode gain is zero. This 79 _IlR__ III 1111111 *11---___·11 IResponsel ZResponse 0 1 01 D=1 IwaveAl = IwaveBI = 1 : f = / (waveA) - 1 00 r . " \ (waveBl 1) U) -1 10 c O 0n 0c) -0.5 -2 10 rC oU Ul -3 10 -4 10 - . . . ...r -0.5 . 1 . . . -1.0 I ! Fm· ! . ! - -0.5 0.5 0 L . . . . I - - - 0.5 0 V y (cycles) : (cycles) 0 1 01 1 00 () c0 a) -4 10 D=j IwaveAl = IwaveBi = 1 -6 .3 10 -0.5 U) o -2 10 nC 0 -1 10 = Z (waveA) - Z (waveB) . . . . -0.5 . . . . · ; I.. ! : - !_ 0.5 0.5 r (D C: c -1 0 rcoN. 0 (D, U 0 -2 CD1 0 D=1 N IwaveAl =2*lwaveBI = 2 = Z (waveA)- Z (waveB) 10 - 3 . 4 . -0.5 - f (cycles) 0 10 ... - . - 0 (cycles) 1 0° c: 1 0 F--, -0.5 1 01 0 I - - - - . 0.5 0 V -1 . I . . . . . - - 0 . . . -0 5 I E. . . . . V.w -0.5 0.5 y (cycles) . . . r 0 . . I . 0.5 xV (cycles) Figure 6-9: Model behavior when C=0 and (A) D=i, IwaveAl = IwaveBI; (B) D=j, IwaveAI = IwaveBI; (C) D=I, IwaveAI = 21waveBI . 80 situation is described by the pressure-difference assumption (Equation 1.1). Under these conditions Vcpl should be limited by the noisefloor at b = 0 whenever IPowl = IPRwI. During most of the measurements, attempts were made to keep IPowI = IPRwI, but it was not uncommon for IPowl to differ from IPRWI by about 0.05 to 0.1 dB SPL (the resolution of the attenuators which set IPowl and IPRWI was 0.1 dB). If IPowl IPRwI, the dynamic range of the magnitude response is limited Maximum Response Dynamic Range = Minimum Response IVcpl-o=0.5 IPOW+ PRWI IVcPI,=O IPow - PRWI (6.3) The following example illustrates the effect of a small difference between IPowl and IPRwI on the total dynamic range of the response. Suppose IPowl = 2 Pa = 100dB SPL (6.4) IPRwI= 2.01 Pa = 100.05dB SPL. (6.5) and The maximum response is proportional to the maximum effectiveinput stimulus I(Pow- PRW)Jp=0.5= 4.01 Pa ~ 106 dB SPL (6.6) and the minimum response is proportional to the minimum effectiveinput stimulus I(Pow - PRw),0=o = -0.01 Pa z 55 dB SPL. (6.7) The total dynamic range is the ratio of these two values. Dynamic Range = 51 dB (6.8) IPowI and IPRwI differ by only 0.05 dB SPL in this example, but the dynamic range is 51 dB. Most of the measurement sets shown in Appendix C have dynamic ranges between 40 and 50 dB. The observed dynamic range is limited not only by our ability to set IPowI = IPRWI, but also by our ability to measure a response at exactly b = 0. If IPowI = IPRWIbut the measurement made closest to LPo w = LPRW is really LPow = LPRw + 0.01 cycles 81 rUII__·__N_______C_____I_·IIU·IIY·-PI such that ,p = +0.01 cycles, the maximum dynamic range of Vcpl is limited to 26 dB. Here is an example to illustrate this limitation. Suppose IPowl= 2 Pa = 100dB SPL (6.9) IPRWJ= 2 Pa = 100dB SPL. (6.10) and The maximum response is proportional to the maximum effective input stimulus I(Pow - PRw)I0=o.5= 4 Pa - 106dB SPL (6.11) and the minimum response is proportional to the minimum effective input stimulus I(Pow - PRW)I,=O.Ox = 12- 2e001 'j Pa - 0.13 Pa m 80 dB SPL (6.12) The total dynamic range is the ratio of these two values. Dynamic Range = 26 dB In the same way, a measurement made such that measurement made to 4' = (6.13) = +0.001 ± cycles is the closest 0 gives a maximum dynamic range of about 55 dB. It is clear that mismatches in magnitude as small as 0.05 dB in magnitude and 0.001cycles in angle can have severe effects on the minimum Ivcl value that is measured in a given measurement set, if C = 0. Non-zero common-mode gain This section presents examples constructed to examine the behavior of Equation 6.1 when both IDI and ICi are nonzero. Only cases where IDI >> CI are presented because the experimental results and model predictions shown earlier in this chapter suggest that IDI >> jCl for the cat cochlear system. The examples here use DI = 1 and ICl = 0.1 which corresponds to CMRR = 20 dB. Smaller values of CJ are not used because as the difference between IDI and ICI increases (as CMRR increases) it becomes more difficult to observe visually the effects of C on Response in Equation 6.1. Three interesting cases are illustrated in Fig. 6-10. 82 1. Fig. 6-10A shows that when D and C have the same angle, and ID} >> C, IResponsej is a minimum at Ob= 0 and LResponse makes a 0.5 cycle transition near b = 0. The difference between this case and the one shown in Fig.6-9A, where C = 0, is that at 0b = 0 the minimum in magnitude is limited by the commonmode component to be C(waveA + waveB) and can never be zero, and the angle changes more slowly around = 0. 2. Fig. 6-10B shows that when D and C differ in angle by 0.25 cycles the minimum value of Responsel does not occur at Ob= 0, the 0.5 cycle transition in angle is not centered at ~b = 0, and the minimum of IResponsel is zero. For this special case Responsel = 0 at b = 0.016 cycles (see discussion below). Additionally, the dynamic range of IResponsel is infinite (only 70 dB shows due to finite sampling resolution), but CMRR is still 20 dB. 3. Fig. 6-10C shows that when D and C have angles that differ by amounts other than ±j, the minimum value of Responsel does not generally occur at b = 0, the 0.5 cycle transition in angle does not generally occur at b = 0, and the minimum of Responsel is not generally zero. For this case the minimum value of IResponsej occurs at b = 0.01 and the minimum of IResponse is 0.07. To summarize, when IDI >> ICI and LD = LC, IResponsel goes to a minimum at 00b= and this magnitude minimum is determined by {C. When LD and LC are not equal the magnitude minimum does not occur at -b= 0 and Responsel can have a larger dynamic range than when D = LC. For the special case of ZD differing from C by ±0.25 cycles there exists a value of b, 0b0 , such that Responsel goes to zero. If Response = 0 = D(waveA - waveB) + C(waveA + waveB) the ratio can be determined as D 1 1+ C 2 where (6.14) waveA __, __- 1 14+Xej-6 (6.15) (° 1,, 2 1-XeJ eA = Xej'o, X is the ratio between {waveAI and IwaveBi, and 0 is the phase difference between waveA and waveB when Responsel = 0. When X = 1, as in Fig. 6-10B, the solution of Equation 6.15 can be approximated as i -1 O CCD =_ jsin(,bo) 83 (6.16) lResponsel ZResponse 0.5 01 1 00 () 0C. 10 0, CE 26dB 1 r I 00 0, 2 10 10 -3 10 4 0) 01 D=1 C=0.1 IwaveAl = IwaveBI = 1 yr= Z (waveA) - Z (waveB) __ .__ = . -0.5 .. . ... - - -n,.,v ! . i -0.5 0.5 0 _, !I ; _._, 0.5 0 -W (cycles) -r (cycles) 1 01 0 1 00 (C, co -1 0. 10 0 a) 0, Cc - 10 2 CE -0.5 D=j C=0.1 N 10 3 10 -4 IwaveAl = IwaveBI = 1 = Z (waveA) - Z (waveB) -1.0 -0.5 0.5 0 i L... . .. I -0.5 0 I 0 0.5 y (cycles) Nf (cycles) 1 01 0.5 -I1 00 0 0CE 10 a) c, 29 dB -1 0r CEL 0 1 0-2 r- N i =IwaveB . V = 1 NaveA)- Z (waveB) 1 0' -4 F _· -0.5 . · - - 0 - - -0.5 ! -0.5 0.5 v (cycles) 0 0.5 xr (cycles) Figure 6-10: Model behavior when waveAl = IwaveBI and (A) D=1, C=0.1; (B) D=j, C=0.1; (C) D = (1+j), C=0.1. In all three cases CMRR=20 dB. 84 or 1 ,bo= sin .C (j3) (6.17) Equation 6.17 has solutions only when ZD differs from LC by +0.25cycles; thus Responsej can go to zero only under this special condition. 6.3.2 Why is it difficult to estimate C? We have seen that the dynamic ranges of the experimental measurement sets can be limited by several factors. 1. Small deviations from IPowl = PRw] 2. The inability to make measurements at exactly bMIN 3. Noisefloors 4. Contributions of a common-modecomponent to the response It is difficult to separate the effects of these factors from each other and from measurement errors in Pow and PRW. To better understand the contribution of the difference-mode and common-mode components to the total cochlear response, as a function of 0b,Equation 3.1 is decomposed. If Powl and IPRwl ae exactly equal then D can be found directly when Ob= 0.5 and C can be found directly when 4b= 0. VCP D Pow - PRW C 2 VCP 1 C(POW + PRW) 2 POW - PRW POW +PRW D(POW - PRW) Pow + PRW VCP POW - PRW =2 VCP (6.18) VP 2POW VCP Pow + Pw I=0= Pow I=o (6.19) Equation 6.18 can yield a robust estimate of D even when pbonly approximates 0.5 cycles because IlcpI is large and does not change rapidly when 'b = 0.5, and the term is much larger than the term (PO-W+PRW). P-PRW However, when 85 VCp POW-PRW ICJ << IDI and there are just slight deviations from Pow = PRW in either magnitude or angle, Equation 6.19 can make large errors in the estimates of C because VcpJ changes rapidly when 'b ~ 0, and the term 2 Pow+PRW +P is on the same order as the term D(POW-PRW) Therefore, Pow+PR when ICI<< IDi, the common-mode response only dominates Vp when Pow = PRW and the difference-mode response is much less than the common-mode response. It is difficult to make the difference-mode component of the response go to zero, or at least become smaller than the common-mode component of the response, because b is never exactly zero and IPowl is never exactly equal to IPRwJ. As a result, the estimate of C is highly dependent on both the resolution of the measurement system and errors in a single measurement, while the estimate of D is not significantly affected by such factors. 6.3.3 How much is the estimate of C affected by small errors in pressure measurements? The discussion in Chapter 4 suggests that errors in the measurements of Pow and PRW are probably less than 0.5 dB in magnitude and 0.01 cycles in angle; here we examine the effects of such errors on the estimates D, C, and CbMRR. To examine the effects of the errors in IPowi, IPRWI,LPow, and LPRw, the measured Vcp and PRW values from the measurement set labeled "1000f7" shown in Fig. 6-2 are held constant while errors that range from -0.5 to 0.5 dB in magnitude and -0.01 to 0.01cycles in angle are added to the measured value of Pow. Newestimates of D, C, and CMRR are computed from Equation 3.1 for each combination of magnitude and angle error. Fig. 6-11 shows effects on D and C of small errors in the measurement of Pow. The errors have little effect on DI or ZD but there are large changes in C and LC. The ratio between the maximum and minimum values of IDI is nearly 1 (1.07), and the difference 86 log 10 log IDI 10 ICI -5.36 -5.38 0.01 t6o0 6i ZC (cycles) ZD (cycles) Figure 6-11: Estimates of D and C made for combinations of small errors in the magnitude and angle of Pow. The errors in pressure magnitude range from -0.5 to 0.5 dB and the errors in pressure angle range from -0.01 to 0.01 cycles. 87 Co Er 0.5 i d05 Figure 6-12: Estimates of CMRR made for combinations of small errors in the magnitude and angle of Pow. The errors in pressure magnitude range from -0.5 to 0.5 dB and the errors in pressure angle range from -0.01 to 0.01 cycles. Contour lines for CMRR = 50,40,30,25 are drawn in the CMRR = 0 plane. 88 between the maximum and minimum values of LD is less than 0.01 cycles. However, the ratio between the maximum and minimum values of C[ is infinite; if the plotted points had been sampled more densely this would be visible from Fig. 6-11. The angle LC takes values from -0.5 to 0.5 cycles. Since CMRR is computed directly from D and C, it is not surprising that CMRR shows the same type of variation as I; and angle error where [_C[goes to zero, CMRR at the magnitude goes to infinity (Fig. 6-12). The procedure illustrated here, introducing errors in the measured values of Powl and LPow and calculating D, C, and CMRR from each synthesized value of IPowl and ZPow, was performed on all measurement sets from Cats #4 to #7. A plot of CMiRR such as the one shown in Fig. 6-12 was formed with ranges of ±0.5 dB in magnitude and ±0.01 cycles in angle from the original measurement. In most cases a large peak occurred at some point on the plot (the location varied) while the minimum CIMRR value was never less than about 20 dB. In a few cases the maximum peak of the mesh was not contained within 0.5 dB in magnitude and 0.01 cycles in angle from the original measurement, but part of the peaked area always existed within this range. The position of the peak in the CMRR vs. Pow error analyses did not stay constant among measurement sets. In some cases consecutive measurement sets made at the same frequency and level, and with no movement of the microphone and sound-source assemblies, predict peaks in the CMRR plots that are in different quadrants. This suggests that something about the cochlear-potential response changed with time; based on the result shown in Fig. 4-3 it does not seem possible that the microphone responses could change by up to 0.2 dB in magnitude and 0.005 cycles in angle in a small amount of time when the microphone and sound-source assemblies were not touched. To summarize, small errors in Pow and PRW, and possibly small changes in the 89 cochlear-potential sensitivity, can cause large variations in the estimate C and thus CMRR. The upper-bound of C, or the lower bound of CMRR, remains approximately constant for the error range examined here; CMRR is rarely less than 20 dB at any frequency for any combination of magnitude and angle error introduced here. On the other hand, the lower-bound of C, or the upper bound of CMRR, is more difficult to define. CMRR has a peak value of infinity (or CI has a minimum value of 0) for some combination of magnitude and angle error introduced here in almost all of the measurement sets. These large dependencies of CMRR and C on the precision of the pressure measurements coupled with a possible change in cochlear sensitivity over time makes it impossible to determine an upper bound for CMRR other than infinity from our measurements. 6.3.4 Comparison to Wever and Lawrence The experimentally measured minimum of Vcpl occurs at a difference in phase between the oval and round-window sound pressures b = IbMINdat,a- IMINdata is an interesting quantity because it helps describe D and C. IfC = 0, ,bMINd,t must equal zero, but more generally bMINv,,d is also equal to zero when LD = LC (Chapter 6.3.1). In some of the measurements bMINda, occurs when Vcpl is below the noisefloor, and the precise value is not known. However,the minimum magnitude of the model prediction, of 0bMINdata is always known. A t-test of the null hypothesis "the Vcp, which occurs at bMINmodeL, and the mean value of mean value of 0bMINdata kbMINm,de, are the same", shows that there are not statistically significant differences between these two mean values at 100, 300, and 1000 Hz (p = 0.01). Additionally, t-tests of the null hypotheses "the mean value of bMNdta is equal to zero" and "the mean value of 0MINoe,, 90 is equal to zero", show that there are not statistically significant differences between the mean value of OMINdat, and MIlNdata= 0 and the mean value of MINdata and IMINmodel = 0 at 100, 300, and 1000 Hz (p = 0.01). Since the minimum magnitude of the model prediction, Vcp, occurs at '? = /MINmodel O, we use OMINnmdel to represent the experimental ?MINdt. VbMINdota results. 0.02 * uI-- a) 0.01 o 0 0 C r0 4- 0o _0 ._ 0 0 o E zZ -0.01 -A O O O Mean and std (shifted -20 Hz) Cat #4 (shifted -10 Hz) Cat #5 (shifted 0 Hz) Cat #6 (shifted 10 Hz) Cat #7 (shifted 20 Hz) -0.02 0 400 200 600 800 1000 Frequency (Hz) Figure 6-13: ,bMINmodel,the difference in phase between the oval and round-window pressures at which the minimum magnitude of the model prediction Vfp occurs, for each measurement set from Cats #4 to #7. To increase legibility, points for a given cat are shifted right or left by a small amount, as indicated in the keys. Fig.6-13 plots 1MINmOdel as a function of frequency; 91 . _._ .`~"""~~~~"~~-I"~" ?IMINmodel is within O.02cycles of 0.5 0.4 co 0.3 C.), z ~. 0.2 0.1 0 8 Z 100 21 4 1b Z /U 1000 J 4 3 I/I 10000 Frequency (Hz) Figure 6-14: Comparison of ObMINdaafrom Wever and Lawrence (1950) with the model prediction ,bMINmodel from the data presented here. There are minor differences in ,MINmodel and OMINdta found in this thesis; see text for details. 92 IVcpl (dB re 1 V) ZVp (cycles) -80 - .5I- -90 CMRR =14.05 IDI = 5.63e-6 /D = -0.446 ICI = 1.12e-6 /C = 0.291 -100 -110 040 - _ - -140r :: : a a :: -0.5 0.0 I1 1 ~ r- -~~~~~~~~·,\ , , MINIVIUUel= V.V 318 :I 0.5 -0.5 W (cycles) Figure 6-15: Pmag = 0.996 a, = 0.973 MI ta_ .03;-,,,o~ MIN Data = 0.031(05 tN -120 Data from measurement 0.0 0.5 Mi(cycles) "1000c_7" of this thesis shifted such that 4 'MINdat = 0.03 cycles in order to correspond to the result of Wever and Lawrence (1950). The linear fit to this shifted data results in CMiRR = 14dB, a decrease of 21dB from the result found in this thesis. ; = 0 for all measurement sets from Cats #4 to #7. Fig.6-14 compares the means values of bMIN,Ode, found here to the values of IbMINd,a measured by Wever and Lawrence (1950). The Wever and Lawrence values appear significantly different from ObMINd,ta 0 for frequencies between 100 and 1000 Hz, but the measurements reported in this thesis suggest that IMINdata and ?bMINmodeloccur at k 0. Differences between the results found in this thesis and those found by Wever and Lawrence are illustrated as follows. The Obvalues from the data of measurement set "1000c_7", shown in Fig. 6-2, are shifted by 0.03 cycles (the ObMINda,treported by Wever and Lawrence, 1950) and the least-squares fit is again applied to the data. This result is shown in Fig. 6-15; the shifted data is barely distinguishable from the result in Fig. 6-2. However the shift of only 0.03 cycles in ibMINd,ta has a significant affect on the estimates of C and CMRR; this shift increases ICI from 1.04 * 10- 7 to 1.12 * 10- 6 and reduces 93 CMRR from 35dB to 14dB. Thus the results of Wever and Lawrence suggest much lower CMRR values than those found here. The nonzero values of OMIN reported by Wever and Lawrence between 100 and 1000 Hz are suggestive of a significant common-mode component of the cochlear-potential response. 6.3.5 Comments on the Bekesy result Audiometric results from B6kesy (1936a; 1960, Fig. 5-10) suggestive of a nonzero commonmode gain were discussed in Chapter 1.3. Briefly, using ears with no ossicles Bekesy measured an increase in hearing sensitivity as frequency decreased; it is presumed that this increased sensitivity was correlated with a decrease in the pressure difference between the oval and round windows. If this is true, such a result is not consistent with the experimental results of this thesis. However, several factors can possibly explain the Bk6sy result. The threshold measurements performed on the ears with no ossicles do not necessarily measure the threshold of hearing of the ossicle-less ear. Instead, the thresholds are determined by the most sensitive sensation to an acoustic stimulus presented to the ear with a head phone. One possibility is that a tactile sensation had a lower threshold than the hearing sensation for the subjects tested. Between 5 and 20 Hz the average threshold measured on these subjects is within one order of magnitude of one measure of tactile thresholds to intense sound stimuli (B4kesy 1936b; 1960, Fig. 7-48). Another possibility is that acoustic crosstalk" occurred between the earphone and the contralateral "normal" ear. It does not appear that potential responses from the normal ear were masked. 94 Chapter 7 Summary Experimental results which directly support the common assumption that the cochlea responds to the difference in pressure between the oval and round windows were presented. The cochlear response was represented as two components: the difference-mode response results from the difference in pressure between the oval and round windows and the common-moderesponse results from the summation in the pressures at the oval and round windows. The common-mode response was difficult to measure because it was small compared to the total cochlear response. A conservative summary of our data is that the common-modegain is at least one order of magnitude smaller than the difference-mode gain. However, most of our data is also consistent with a common-mode gain of zero. Thus the ratio between the difference-mode gain and the common-mode gain, CMRR, is between 20 dB and infinity. It is not trivial to put a tighter bound on this large CMRR range. To decrease the current range, the uncertainties in pressure measurements of less than 0.5 dB in magnitude and 0.01 cycles in angle must be reduced. Also, further study of how the cochlear-potential response changes with time is needed. 95 The importance of the difference-mode response to hearing suggests that procedures such as the type IV tympanoplasty should improve hearing in ears with no ossicles. Surgeons should continue attempts to maximize the pressure difference between the oval and round windows. 96 Appendix A Summary of experimental animals and calibrations Appendix A summarizes all experiments used to develop the methodology and to obtain results for this thesis. Information specific to each cat is briefly discussed. Measurements of the acoustic isolation between Pow and PRW, as shown in Fig. 2-3, are presented for each experimental animal. Also, changes in the calibrations of the sound-source and microphone assemblies, as depicted in Fig. 4-1 and 4-2, are shown for each experiment. Measurements used to define all noisefloors are displayed in tables. Responses from Cats #6 and #7 to clicksand tone bursts are shownfor both pre and post-TTX measurements. A.1 Brief description of each experiment Cat#1: July 14, 1993 Both single-sided and simultaneous-stimuli measurements were made on the left ear. The sound sources were not re-calibrated during the experiment. At the end of the 97 experiment a calibration was performed and the result was significantly different from the calibration at the beginning of the experiment; the sound-pressure measurements of magnitude and angle by the oval and round-window microphones are questionable to within several dB in magnitude and several degrees in angle. At the end of the experiment the earcanal was found to be full of fluid a few minutes after the removal of the oval-window sound source and microphone. It is not known how much of this fluid was in the earcanal and middle-ear space during the experiment or how much of the fluid seeped into the earcanal from the tissue surrounding the meatus after the removal of the microphone. Additionally, condensation was present on the diaphragm of the earcanal microphone. There was no fluid in the bulla cavity and no condensation on the round-window microphone. The round window looked opaque and vascular; it is possible that an infection existed. In subsequent experiments the sound systems were recalibrated several times over the course of the experiment, the middle-ear air spaces were monitored and the cats were given penicillin to fight infections. Cat#2: July 27, 1993 Severe bleeding occurred during the first attempt to plug the foramen of the left middleear space. The right ear was surgically prepared and more severe bleeding occurred when the external carotid was cut. The cat survived and single-sided and simultaneous-stimuli measurements were made but responses were not repeatable during the simultaneous stimuli measurements. Additionally muscular activity superimposed on the cochlearpotential response was observed. 98 Cat#3: August 5, 1993 There were no physiologic problems with the cat. Numerous single-sided and simultaneousstimuli measurements were made on the left ear. In several cases the pressures at the two windows were not equal in magnitude; instead the pressures were chosen such that the resultant single-sided cochlear-potential magnitudes were equal. The system was re-calibrated several times during the experiment. Variations in calibrations occurred which were significantly greater than those in the final four experiments. The stability of the acoustic systems was increased substantially after this experiment. Parts of the couplers between the sound-sources and microphones were modified to have tighter fits. This alteration allowed the acoustic assemblies to be moved without large changes in calibration (Chapter 4). Cat#4: September 22, 1993 There were no physiologic problems with the cat. The acoustic systems were re-calibrated several times during the experiment and the changes in calibration were much smaller than previous experiments; these changes were on the order of a few tenths of a dB in magnitude and a hundredth of a cycle in angle (Fig. A-12 and A-13). Measurements were made at 75 Hz, 100 Hz, 250 Hz, 500 Hz, 800 Hz, and 1000 Hz. Prior to this experiment the cochlear-potential electrode was coupled through a 1000 n resistor to ground. Radiation from the sound sources at maximum input levels did not produce an electrical artifact that could be recorded by the resistor - electrode system. 99 Cat#5: March 21, 1994 There were no physiologic problems with the cat. The acoustic systems were re-calibrated several times during the experiment and the changes in calibration were less than 0.2 dB in magnitude and less than 0.003 cycles in angle (Fig. A-14 and A-15). After each calibration a small brass tube was used to couple the two sound-source and microphone assemblies together. A sound common to both microphones was produced and it was confirmed that the two microphone calibrations were consistent. This procedure was repeated after the assemblies were decoupled from the cat. Measurements were made at 100 Hz, 300 Hz, and 1000 Hz on the right ear. The effect of artifactual coupling from the earphones to the cochlear-potential electrode was not checked. The distance from the oval window to the position of the probe tube in the earcanal was measured to be 4.9 mm, and the distance from the round window to the position of the probe tube on the bulla cavity was measured to be 7.6 mm; the difference is 2.7 mm. Cat#6: August 11, 1994 There were no physiologic problems with the cat. The system was re-calibrated several times during the experiment and the changes were less than 0.2 dB in magnitude and less than 0.004 cycles in angle (Fig. A-16 and A-17). The calibrations were checked with the small brass tube described above. Measurements were made at 100 Hz, 300 Hz, and 1000 Hz on the right ear. TTX was applied to reduce the neural component of the cochlearpotential response (CAP). A significant electrical artifact from the sound source was found at the end of the experiment. When the sound sources were plugged with cotton and then recoupled to the cat the round-window-electrode response increased linearly with input voltage. The highest levels were comparable to and possibly greater than 100 the lowest cochlear-potential measurements made during the experiment; it is likely that the simultaneous-stimuli cochlear-potential measurements were contaminated by this electrical artifact when Vcp| was near a minimum. Cat#7: September 8, 1994 There were no physiologic problems with the cat. The system was re-calibrated several times during the experiment and the changes were less than 0.8 dB in magnitude and less than 0.015 cycles in angle (Fig. A-18 and A-19). Measurements were made at 100 Hz, 300 Hz, and 1000 Hz on the right ear. The calibrations were checked with the small brass tube described above. TTX was applied to eliminate the neural component of the cochlear-potential response. All cables used in the experiments were shielded and no electrical artifact was detectable. 101 A.2 Acoustic crosstalk for each animal 102 OW SOURCE OFF OW SOURCE ON RW SOURCE OFF 100 - 80 m 'O RW SOURCE ON ......... IVRW.mNDACowI/ 80 60 M 0 40 ........A 4Arj. . .t4 20 I 2 1 00 - I i : f I I 4 I I11 1000 2 I I . .= 40 A .Ii I 4 _ I 2 100 ZVOW - ZVDACow ......... 0.5 I I 4 I I Ii l 6 8 1 000 I I 1 2 4 4 4 VOW-VVDACRw RW, c- VDACRw 0.5 co C O1 o.................. 60 VRW .........-/V DACow a) W -IVOWV.NDACRw · ........ IVRW.VNDACRWI ....................... . 20 ?f 6 8 K 1 00 IVow,,DACow cn a) ) 0.0 0.0 >1 -0.5 100 -0.5 1000 100 Frequency (Hz) 1000 Frequency (Hz) Figure A-1: Measurements of acoustic crosstalk between the tympanic and bulla cavities from Cat #1. LEFT: Measurement of the transfer function between the oval-window microphone response Vowm,, and the oval-window sound-source input VDACOW, and measurement of the transfer function between the round-window microphone response VRWmiCand the oval-window sound-source input VDACow. The round-window sound-source was off. RIGHT: Measurement of the transfer function between the oval-window microphone response Vow,ic and the round-window sound-source input VDACRW, and measurement of the transfer function between the round-window microphone response VRw,m, and the round-window sound-source input VDACRW. The oval-window sound-source was off. 103 OW SOURCE ON RW SOURCE OFF OW SOURCE OFF RW SOURCE ON 0 U -20 m 0 - -40 - -60 - - IVOWmCVNDACOWI ......... IVRW,. NDACowI -20 .. -60 -80 I........................................... v 100 I I 2 4 ZV ......... I I I _'"**"°"'" I ] '°°*'°° 6 8 1000 I 2 I -100 . I 4 I 1 00 2 4 6 8 1000 OWmic ..V-ZVDACow OW 2 4 DACRW ZVRWmiCZVDACRw VRWmjcZV DACow 0.5 ....... 0.5 a, a) <n a) Co IVowmicNDACRw IVRWmi/DACRWI -40 E -80 -10(To _ ......... 0.0 0 >1 0.0 0 0 -0.5 -0.5 100 Z 0 l4 Z Z 4 1000 1 00 4 0 Z 4 1000 Frequency (Hz) Frequency (Hz) Figure A-2: Measurements of acoustic crosstalk between the tympanic and bulla cavities from Cat #2. LEFT: Measurement of the transfer function between the oval-window microphone response VOWmic and the oval-window sound-source input VDACow, and measurement of the transfer function between the round-window microphone response VRWmic and the oval-window sound-source input VDACOw. The round-window sound-source was off. RIGHT: Measurement of the transfer function between the oval-window microphone response Vow,mI and the round-window sound-source input VDACRW, and measurement of the transfer function between the round-window microphone response VRWmCand the round-window sound-source input VDACRw. The oval-window sound-source was off. 104 OW SOURCE OFF RW SOURCE ON OW SOURCE ON RW SOURCE OFF 0 U - -20 _ -40 m a - IVOWm DACRw IVOWNVDACowI -20 .--..... VRWVADACo - --- m -60 _ -40 _ "I'", IVRW, DACI I -60 -80 -80 ,-A" I -100 --- I 100 -1in Iy 2 4 6 8 1000 2 4 r I I 4 100 ZVow'ZVDACow 1111 68 2 1000 4 ZVOWmic "VDACRW ......... ZVRWm= VDACow -- 0.5 U.5 A I 2 ......... ZVRW,,ZVDAC .. en (D 0cu 0.0 0 -0.5 -0.5 1000 100 100 4 6 8 - 1000 Z 4 Frequency (Hz) Frequency (Hz) Figure A-3: Z Measurements of acoustic crosstalk between the tympanic and bulla cavities from Cat #3. LEFT: Measurement of the transfer function between the oval-window microphone response Vow,,c and the oval-window sound-source input VDACow, and measurement of the transfer function between the round-window microphone response VRWm,i and the oval-window sound-source input VDACOW. The round-window sound-source was off. RIGHT: Measurement of the transfer function between the oval-window microphone response Vowmjc and the round-window sound-source input VDAC,w, and measurement of the transfer function between the round-window microphone response VRWmi, and the round-window sound-source input VDACRW. The oval-window sound-source was off. 105 OW SOURCE ON RW SOURCE OFF 0 -20 m: OW SOURCE OFF RW SOURCE ON 0 VowmNDACowI VRW.NDACOWI ......... m -80 -100 ... .. .......................................... 2 1 00 -LVo 0.5 4 68 1000 2 -40 :, -80 -100 .. ........ . ....... ."""" -60 ... ......... \ y..-,.% V 6'8 IVOW. NDACRWI -20 -40 -60 - - 4 i ,,, . 68 100 -ZLVDACW - ......... /VRWmc -ZVDACOW 0.5 u, a, u, 01 C. 0 0.0 0 -0.5 2 I I I .11111 4 68' 1000 I 2 I I 4 ZVOW-ZVDACRw RWm cZVDACRw ......... 0.0 -0.5 100 1000 100 Frequency (Hz) 1000 Frequency (Hz) Figure A-4: Measurements of acoustic crosstalk between the tympanic and bulla cavities from Cat #4. LEFT: Measurement of the transfer function between the oval-window microphone response VoWmic and the oval-window sound-source input VDACOW, and measurement of the transfer function between the round-window microphone response VRWmc and the oval-window sound-source input VDACOW. The round-window sound-source was off. RIGHT: Measurement of the transfer function between the oval-window microphone response VOWmicand the round-window sound-source input VDACRW, and measurement of the transfer function between the round-window microphone response VRWmic and the round-window sound-source input VDACRw. The oval-window sound-source was off. 106 OW SOURCE OFF OW SOURCE ON RW SOURCE OFF RW SOURCE ON 0 0 -20 -20 -40 -40 -- IVowN/DAC.WI i....... iVRW NDACW I .. m VD m a -60 -60 -80 -80 -100 -100 ..... .l. . 68 2 4 100 _ ZVOW,-VDACow 0.5 0.5 0.0 ' 0.0 -0.5 -0.5 n 2 1000 4 ......... ZVRWmc -ZVDACR a) 100 1000 100 1000 Measurements of acoustic crosstalk between the tympanic cavities from Cat #5. c S l Frequency (Hz) Frequency (Hz) Figure A-5: 6 81 ZOWW -ZVDACRw ......... LVRW,, -LVDAw 0 .t. ...... and bulla LEFT: Measurement of the transfer function between the oval-window microphone response Vowc, and the oval-window sound-source input VDACOW, and measurement of the transfer function between the round-window microphone response VRWmi, and the oval-window sound-source input VDACOW. The round-window sound-source was off. RIGHT: Measurement of the transfer function between the oval-window microphone response Vowmtc and the round-window sound-source input VDACRW,and measurement of the transfer function between the round-window microphone response VRWmicand the round-window sound-source input VDACRW. The oval-window sound-source was off. 107 OW SOURCE OFF RW SOURCE ON OW SOURCE ON RW SOURCE OFF - -40 -60 m ' -80 -1 IVOWm,,cVDACowl -40 IVRW NDACowI .......... IC,* A -60 - m - 00 _ -120 1111 6 8 100 2 - - - -_ _ I I 4 I 6 8 2 1000 I ......... VRWmic I I 4 I I1j 6 8 1000 I 2 I ZVOWmi -ZVDACRw ......... ZVRWcZVDACRw DACow 0.5 (I, a0, (, c 2 1 00 U.b a) I 68 ZVVOWi-ZVDACow - .. ~~~~224~~~~~~ I I1111 4 I _~~~~~~~~~~'· -80 -120 * 111111 IVRW NDAC """'"........_ -100 - _ _-, %: IVOWm,,VDACRWI - ......... 0.0 0.0 0 cJ -0.5 -0.5 100 1000 I Ir 100 1000 Frequency (Hz) Frequency (Hz) Figure A-6: Measurements of acoustic crosstalk between the tympanic and bulla cavities from Cat #6. LEFT: Measurement of the transfer function between the oval-window microphone response Vow,,ic and the oval-window sound-source input VDACow, and measurement of the transfer function between the round-window microphone response VRWmic and the oval-window sound-source input VDACOW. The round-window sound-source was off. RIGHT: Measurement of the transfer function between the oval-window microphone response VOWmicand the round-window sound-source input VDACRW, and measurement of the transfer function between the round-window microphone response VRWmi, and the round-window sound-source input VDACRW. The oval-window sound-source was off. 108 I 4 OW SOURCE ON RW SOURCE OFF 0 - -O 0 IVOWmNDACowI IVOWmCNDACRw ·.~... '''.s.. '~' . | VRWmk/NDACowI -20 m OW SOURCE OFF RW SOURCE ON -40 -20 m 'O -60 _ ~~~~~~~~~~~:- i)C`yr, ~~~~.%.. ~,¢: I!V -80 -100 ' 1 ' ' 111111 4 68 2 IlT' 68 100 I a 2 ......... IVRW,, NDACRw -40 -80 -100 I 4 , liI 68 1000 ZVOW ZVDACow ... ... Z V RWm Z V DA... C ow 1 2 100 , I 1 ,II 4 6 8 1000 I I I 2 4 ZVVoWmli-VDACRW ......... ZVRWmic-ZVDACRw 0.5 0.5 () a) I-" -60 (I) a) 0.0 0 0) c) 0.0 O -0.5 -0.5 b u 100 Z 4 t b Z 0 4 b Z 100 1000 Frequency (Hz) 4 t b 4 1000 Frequency (Hz) Figure A-7: Measurements of acoustic crosstalk between the tympanic and bulla cavities from Cat #7. LEFT: Measurement of the transfer function between the oval-window microphone response Vowmic and the oval-window sound-source input VDACow, and measurement of the transfer function between the round-window microphone response VRwmic and the oval-window sound-source input VDACOW. The round-window sound-source was off. RIGHT: Measurement of the transfer function between the oval-window microphone response Vow,,i and the round-window sound-source input VDACRW, and measurement of the transfer function between the round-window microphone response VRwmiCand the round-window sound-source input VDACRW. The oval-window sound-source was off. 109 A.3 Changes in microphone calibration 110 - A Magnitude A Angle from Original from Original Calibration (cycles) Calibration (dB) -43- OWM,, 0.0c I -0.4C 10 -0.010 20 I 10 0.020 0.010 0.000 1000 Hz - RWMIC 0.4C I 10 20 0.0c I 20 0.020 800 Hz 0.010 0.000 -0.2C -0.010 I 10 10 10 20 0.00 -0.20 20 20 0.010 0.00ooo 600 Hz -0.40 1 -0.010 I I I 10 20 10 0.00 I 0.000 400 Hz -0.10I 20 -0.004 -0.008 -0.20I 20 10 10 0.05 0.00I -0.05 20 0.000 200 Hz -0.004 - - - - - - - - -0.10I I 20 10 . .10 20 10 0.05 0.00 -0.05 I I 0.002 100 Hz 0.000 I I I I I -0.002 - - - - - - - I I 10 20 10 . . . . I . . 20 Time of Day (hours) Time of Day (hours) Figure A-8: The differences in SPL and SPL between the initial calibration and Vomic VRWmic subsequent calibrations during the experiment on Cat #2. The first measurement of SPL ( SPL ) was used to normalize all succeedingmeasurements of VSPL (VSPL ); OW.mic Vmic RW., Wm magnitudes (in dB) and angles (in cycles) of the ratios are plotted. Time of day = 10 hours is the time of initial calibration. 111 Maximum Phase Difference (cycles) Maximum Magnitude Difference (dB) 1.5 u.ut -0- OWMIC -43 OWMI I I-0- RW., I 1.0 p--4 0.02 0.5 0.0 - .0- RWMIC 0.04 0.00 . . I .. .. .. .. .I .. .. . . I 0 500 1000 0 Frequency (Hz) Figure A-9: The maximum changes in during the experiment on Cat #2. ,, . I . . I, .. ....... I ... 500 I 1000 Frequency (Hz) SPL Vow,. ti 112 ySPL as a function of frequency and VRW.i c A Magnitude A Angle from Original from Original Calibration (cycles) Calibration (dB) -- -- ow"'j O0mjc -o- RW, 1.0 1000 Hz 0.5 0.02 k~~d~~l? 0.0 0.00 A A 10 20 30 10 20 30 40 10 0.020 20 30 40 20 30 40 40 U.8 0.02 800 Hz 0.4 0.01 0.0 0.00 10 20 30 40 0.4 600 Hz 0.010 0.0 0.000 . 10 20 30 10 40 0.4 400 Hz 0.010 0.0 0.000 10 20 30 40 0.2 10 20 30 40 0.1 20 30 40 10 20 30 40 0.008 0.004 0.000 200 Hz 0.0 10 0.004 0.002 0.000 I-" 100 Hz 0.0 -0.1 I 10 20 30 40 10 Time of Day (hours) ' I 20 ' I 30 ' I 40 Time of Day (hours) Figure A-10: The differencesin VSPL and SPL between the initial calibration and subsequent calibrations during the experiment on Cat #3. The first measurement of vow. ( VR9W ) was used to normalize all succeeding measurements of VoSPL (VRWP); magnitudes (in dB) and angles (in cycles) of the ratios are plotted. Time of day = 10 hours is the time of initial calibration. 113 Maximum Phase Difference (cycles) Maximum Magnitude Difference (dB) I.u A u.u4 to1 r -1- OW . j -- RW,,~ 0.02 0.5 0.00 0.0 I 0 I I I I I I I I I ,I I 500 1000 Frequency (Hz) Figure A-ll: The maximum changes in during the experiment on Cat #3. 0 I I I I 500 I I 1000 Frequency (Hz) SPL 114 and SPL as VRWm.ic a function of frequency A Magnitude A Angle from Original Calibration (dB) from Original Calibration (cycles) -- -0- OWt -o- RW, OWm- -0- RMH 1000 Hz .004- 0 .002- -. 2 0800 Hz 0 -.2 20 30 20 30 .002 0 20 30 .0025- 0 500 Hz -.2 - 20 20 30 30 .0025- 0 250 Hz o- -.25 20 I20 30 30 20 30 .008- .2 100 Hz 0 .004- 0- -.2 20 30 75 Hz 20 30 20 30 .01 0 0 20 30 Time-of Day (hours) Time of Day (hours) Figure A-12: The The differencesi differencesin VwFigure SPL and VRWc SPL between the initial calibration and A-12: subsequent calibrations during the experiment on Cat #4. SPL SPL Omi (SRWiPL) The first measurement of SPL RPmic was used to normalize all succeeding measurements of VSPL (VSPL ); magnitudes (in dB) and angles (in cycles) of the ratios are plotted. Time of day = 12 hours is the time of initial calibration. 115 Maximum Magnitude Maximum Phase Difference (dB) Difference (cycles) .0 --O- MM, .5 .0 .4 .0 .3 400 400 800 Frequency (Hz) Frequency (Hz) Figure A-13: The maximum changes in during the experiment on Cat #4. 800 SPL Vow.n 116 and SPL VRWmion as a function of frequency A Angle from Original A Magnitude from Original Calibration (dB) Calibration (cycles) OWic 1000 Hz .1 .001 -o- RWmc 0 -.001 -.002 0 1I 0 5 10 15 .08 300 Hz .04 I 0 5 10 15 0 5 10 I 0 5 10 15 I I I I 0 5 10 15 0 -.0004 0 0 5 10 15 100 Hz .04 0-.001- -.002- 0 0 5 10 15 Time of Day (hours) Time of Day (hours) Figure A-14: The differencesin SPL and SPL between the initial calibration and Vow.;i VRWmisubsequent calibrations during the experiment on Cat #5. The first measurement of PL (RP); ) was used to normalize all succeeding measurements of VoPL (SPL magnitudes (in dB) and angles (in cycles) of the ratios are plotted. Time of day = 0 hours is the time of initial calibration. 117 Maximum Phase Difference (cycles) Maximum Magnitude Difference (dB) .16 .1 6 - -aw 4 - RWr~k .002- .12 \ Fm .0015 - .08 .001 .04 .0005 I 400 800 400 Frequency (Hz) Figure A-15: The maximum changes in during the experiment on Cat #5. 800 Frequency (Hz) SwL and onCat#5. theexperiment oduring 118 as a function of frequency A Angle A Magnitude from Original Calibration (dB) from Original Calibration (cycles) [.1- OW~ .RW_,_I .05 1000 Hz 0 -.05 .001 0 -. 1 .05 .003 .002 20 20 30 30 .001 300 Hz 0 -.05 .0005 0 .05 - 20 30 .0005 0- 100 Hz -.05 0 -.0005 20 30 20 Time of Day (hours) Time of Day (hours) Figure A-16: The differencesin Vow.i SPL 30 and VRwmi¢ SPL between the initial calibration and subsequent calibrations during the experiment on Cat #6. The first measurement of SPL; (V P ) was used to normalize all succeeding measurements of VSPL V iSPL ); magnitudes (in dB) and angles (in cycles) of the ratios are plotted. Time of day = 18 hours is the time of initial calibration. 119 Maximum Magnitude Maximum Phase Difference (cycles) Difference (dB) - OWic -o- RWmw 15.1- .003 rv fly~~~~~~~~~~~~ .002 .001 .05 400 800 400 Frequency (Hz) Figure A-17: The maximum changes in 800 Frequency (Hz) PL during the experiment on Cat #6. 120 and RSPL as a function of frequency VRwric -- A Magnitude A Angle from Original Calibration (dB) from Original Calibration (cycles) W 0.4 1000 Hz 0.0 0.000 -0.005 20 30 40 0.4 + 0.0 - 0.005- oRe 20 I 30 30 40 20 30 40 20 30 40 0.000 300 Hz I 20 -0.002 I 40 0.004 100 Hz 0.4 0.002 0.000 0.0 20 30 40 Time of Day (hours) Figure A-18: The differences in VOL Time of Day (hours) and SPL between the initial calibration and subsequent calibrations during the experiment on Cat #7. The first measurement of SVP (SPgL;;) was used to normalize all succeeding measurements of owm ; magnitudes (in dB) and angles (in cycles) of the ratios are plotted. Time of day = 17 hours is the time of initial calibration. 121 Maximum Magnitude Maximum Phase Difference (cycles) Difference (dB) .015.6.4- {- OWmic -0- RWmi c .01 -I- OWm ic -O- RWmic .005- .2! · 400 800 400 Frequency (Hz) Figure A-19: The maximum changes in during the experiment on Cat #7. 800 Frequency (Hz) SPL 122 and SPL VRWmic as a function of frequency A.4 Noisefloor calculations 123 I Table A.1: Measurements used to define the noisefloor of Vcp from Cat #1. The first 15 rows are the specified frequency component of the VcpJ response to a 1000 Hz tone, in units of dB re 1 volt. These measurements are averaged and used as an estimate of the noisefloor of Vcp. The noisefloor is defined as the mean plus two standard deviations (also in dB re 1 volt). For simplicity the numbers have been rounded to the nearest integer, however, the calculations used more significant digits. 124 NOISEFLOOR MEASUREMENTS: CAT #2 mean std Noisefloor 100 Hz 200 2 Hz 400 Hz 600 Hz 800 Hz -115 -118 -128 -129 -135 -120 -132 -141 -146 -141 -115 -124 -130 -133 -135 -117 -120 -118 -122 -130 -125 -124 -128 -125 -131 -138 -135 -133 -137 -128 -148 -145 -140 -132 -131 -138 -136 -136 -137 -139 -136 -137 -158 -143 -145 -112 -119 -125 -132 -130 -123 -113 -124 -121 -117 -130 -114 -131 -113 -120 6 -108 -125 -135 -130 -131 -128 -149 -124 -130 -121 -129 7 -114 -141 -142 -131 -133 -130 -150 -130 -134 -126 -135 7 -120 -146 -141 -139 -141 -140 -148 -131 -137 -132 -137 6 -126 -138 -139 -141 -137 -138 -141 -133 -143 -132 -139 6 -127 Table A.2: Measurements used to define the noisefloor from Vcp of Cat #2. The first 15 rows are the specified frequency component of the Vcp response to a 1000 Hz tone, in units of dB re 1 volt. These measurements are averaged and used as an estimate of the noisefloor of Vcp. The noisefloor is defined as the mean plus two standard deviations (also in dB re 1 volt). For simplicity the numbers have been rounded to the nearest integer, however, the calculations used more significant digits. 125 NOISEFLOOR MEASUREMENTS: CAT #3 100 Hz 200 Hz 400 Hz 600 Hz 800 Hz mean std Noisefloor -131 -133 -144 -135 -146 -156 -135 -145 -138 -149 -137 -133 -133 -131 -136 -140 -151 -143 -140 -144 -139 -147 -143 -130 -136 -138 -139 7 -125 -135 -133 -134 -131 -138 -142 -135 -137 -136 -137 -136 -132 -133 -134 -134 -134 -135 3 -130 -139 -145 -142 -142 -146 -149 -143 -144 -147 -145 -144 -141 -146 -143 -145 -150 -144 3 -139 -146 -144 -142 -137 -143 -147 -144 -136 -150 -139 -135 -141 -142 -148 -142 -159 -143 6 -131 -145 -147 -140 -143 -148 -141 -147 -145 -147 -143 -149 -154 -147 -138 -148 -150 -146 4 -139 Table A.3: Measurements used to define the noisefloor from Vcp of Cat #3. The first 15 rows are the specified frequency component of the Vcp response to a 1000 Hz tone, in units of dB re 1 volt. These measurements are averaged and used as an estimate of the noisefloor of Vcp. The noisefloor is defined as the mean plus two standard deviations (also in dB re 1 volt). For simplicity the numbers have been rounded to the nearest integer, however, the calculations used more significant digits. 126 NOISEFLOOR MEASUREMENTS: CAT #4 mean std Noisefloor 75 Hz -143 100 Hz -142 250 Hz -149 500 Hz -159 800 Hz -156 -132 -135 -145 -154 -160 -148 -131 -147 -159 -141 -129 -144 -144 -140 -134 -143 -133 -142 -165 -142 -151 -160 -146 -150 -150 -140 -137 -141 -140 -153 -154 -154 -156 -154 -158 -136 -148 -156 -155 -158 -124 -133 -133 -144 -137 -138 -134 -134 -142 -132 -142 -140 -144 -138 6 -126 -127 -131 -137 -144 -142 -132 -141 -151 -150 -142 -134 -141 -139 -139 6 -127 -141 -141 -152 -158 -151 -142 -151 -145 -150 -153 -152 -152 -164 -150 8 -135 -149 -141 -154 -165 -160 -163 -156 -152 -156 -160 -156 -162 -156 -155 6 -143 -149 -147 -162 -150 -157 -156 -151 -156 -154 -155 -151 -163 -169 -154 6 -141 Table A.4: Measurements used to define the noisefloor from Vcp of Cat #4. The first 22 rows are the specified frequency component of the Vcp response to a 1000 Hz tone, in units of dB re 1 volt. These measurements are averaged and used as an estimate of the noisefloor of Vcp. The noisefloor is defined as the mean plus two standard deviations (also in dB re 1 volt). For simplicity the numbers have been rounded to the nearest integer, however, the calculations used more significant digits. 127 I Table A.5: Measurements used to define the noisefloor of Vcp from Cat #5. Either 11 or 6 measurements of Vcp (dB re 1 volt) were made with no stimulus. These measurements are averaged and used as an estimate of the noisefloor of Vcp. The noisefloor is defined as the mean plus two standard deviations (also in dB re 1 volt). For simplicity the numbers have been rounded to the nearest integer, however, the calculations used more significant digits. NOISEFLOOR MEASUREMENTS: CAT #6 100 Hz 300 Hz -149 -149 1000 Hz -147 -148 -151 -155 -158 -147 -143 -159 -147 -154 -150 -151 -149 -145 -154 -148 -147 -143 -146 -148 -146 mean -150 -153 -147 std Noisefloor 5 -140 3 -147 2 -142 Table A.6: Measurements used to define the noisefloor from Vcp of Cat #6. Either 11 or 6 measurements of Vcp (dB re 1 volt) were made with no stimulus. These measurements are averaged and used as an estimate of the noisefloor of Vcp. The noisefloor is defined as the mean plus two standard deviations (also in dB re 1 volt). For simplicity the numbers have been rounded to the nearest integer, however, the calculations used more significant digits. 128 NOISEFLOOR MEASUREMENTS: CAT #7 mean std Noisefloor 100 Hz 300 Hz -139 -155 1000 Hz -132 -165 -158 -130 -131 -133 -154 -156 -143 -161 -150 -159 -141 -134 -139 -167 -138 -136 -138 -152 -155 -158 -164 -160 -160 -156 -148 -160 -155 -158 -148 -153 -154 -148 10 6 5 -118 -144 -144 Table A.7: Measurements used to define the noisefloor from Vcp of Cat #7. 11 measurements of Vcp (dB re 1 volt) were made with no stimulus. These measurements are averaged and used as an estimate of the noisefloor of Vcp. The noisefloor is defined as the mean plus two standard deviations (also in dB re 1 volt). For simplicity the numbers have been rounded to the nearest integer, however, the calculations used more significant digits. 129 A.5 Effects of TTX TTX was added to the cochleas of Cat #6 and Cat #7 in order to eliminate the nonlinear CAP component of the cochlear-potential response (Chapter 2.7). Cochlear-potential measurements were made in response to click and tone-burst stimuli both before and after the application of TTX. Pre and post-TTX cochlear-potential responses to click stimuli (approximately 85 dB SPL) are shown in Fig. A-20 and A-21 for Cat #6 and Cat #7, respectively. In both cases a small cochlear-microphonic response occurs at about 1 ms; the Cat #6 cochlear microphonic is about 5 V (Fig. A-20), and the Cat #7 cochlear microphonic is about 2jV (Fig.A-21). The cochlear-microphonic component of the cochlear-potential response is not affected by the TTX. The responses from both cats also have neural components which occur between about 2 and 4 ms; the peak at about 2 ms is often referred to as the N1 component. The N1 component from Cat #7 is about 20 ,V larger than the N1 component from Cat #6. The N1 and other neural components of the cochlear-potential response are eliminated after the application of TTX; this suggests the TTX successfully blocked at least some of the nonlinear neural response in these animals. Pre and post-TTX cochlear-potential responses to 100 Hz and 1000 Hz tone-burst stimuli (approximately 110 dB SPL) are shown in Fig. A-22, A-23, A-24, and A-25. The Cat #6 cochlear-potential response to a 100 Hz tone burst shows a change after the ap- plication of TTX; the pre-TTX response looks "noisy" and nonlinear whilethe post-TTX response resembles the linear 100 Hz stimulus tone. The pre and post-TTX cochlear- potential responses to a 100 Hz tone burst from Cat #7 are similar and neither response looks as nonlinear as the pre-TTX 100 Hz response from Cat #6. The application of TTX also affected the cochlear-potential response to 1000 Hz tone-burst stimuli. Both 130 the Cat #6 and Cat #7 pre-TTX responses show an initial increased response at about 2 ms; this increase is the neural component of the cochlear-potential response and it is eliminated after the application of TTX. Additionally, the post-TTX 1000Hz tone-burst responses are smaller than the pre-TTX ones. These pre and post-TTX responses suggest that the TTX successfully blocked much of the neural component of the cochlear-potential response. However, as discussed in Chapter 5, some of the post-TTX single-sided level-series measurements made at the lower frequenciesexhibited nonlinearities. It is possible that the TTX was not completely effective at the lowest stimulus frequencies. 131 Click Stimulus 0 0 1 2 4 3 5 6 Time (ms) Click Response 30- 20- - Pre-TTX V) :t 0 10- 0- j -r -10- ts .. , . . . . . … - 4 - I I I I I I 0 1 2 3 4 5 I 6 Time (ms) Figure A-20: Cat #6. TOP: Click stimulus at about 85 dB SPL. BOTTOM: Response to the click stimulus both before and after the application of TTX to the round window membrane. Measurements made between 3 hours and 18 hours after the application of TTX did not show large variations. 132 Click Stimulus o- ...I I I I I I I' 1 0 1 2 3 4 5 6 Time (ms) Click Response 30 - 20Pre-TTX --- Post-TTX (shifted -101V) a. 10- ;>O 0- -10 . . I I I i= · I I I I I I I 0 1 2 3 4 5 6 Time (ms) Figure A-21: Cat #7. TOP: Click stimulus at about 85 dB SPL. BOTTOM: Response to the click stimulus both before and after the application of TTX to the round window membrane. Measurements made between 3 hours and 18 hours after the application of TTX did not show large variations. 133 100 Hz Tone Burst Stimulus 0 0 20 40 60 Time (ms) 80 100 100 Hz Tone Burst Response 50 40 30 20 a. 0 --- Post-TTX (shifted +30pV) Pre-TTX 10 0 -10 -20 0 20 40 60 Time (ms) 80 100 Figure A-22: Cat #6. TOP: 100 Hz tone-burst stimulus at about 110 dB SPL. BOTTOM: Response to 100 Hz tone-burst stimulus before and after application of TTX to the round window membrane. Measurements made between 3 hours and 18 hours after the application of TTX did not show large variations. 134 100 Hz Tone Burst Stimulus 0 100 80 60 40 20 0 Time (ms) 100 Hz Tone Burst Response 50 40- 30- I ... ! I :L a. o 0 .f · ,4 i JI I i I I · ! I I· · · iI · I. V I · * 59I ~,· rr 20- --- Post-TTX (shifted +301zV) - Pre-TTX 10- 0-10 -20 WVVVVVVV~h lL I i 0 20 40 1I I I I 60 80 100 120 Time (ms Figure A-23: Cat #7. TOP: 100 Hz tone-burst stimulus at about 110 dB SPL. BOTTOM: Response to 100 Hz tone-burst stimulus before and after application of TTX to the round window membrane. Measurements made between 3 hours and 18 hours after the application of TTX did not show large variations. 135 1000 Hz Tone Burst Stimulus o 0 2 4 6 8 10 12 14 Time (ms) 1000 Hz Tone Burst Response 400 300 200 a. 0 shifted +300ttV) 100 ;> 0 -100 -200 0 2 4 6 8 10 12 14 Time (ms) Figure A-24: Cat #6. TOP: 1000 Hz tone-burst stimulus at about 110 dB SPL. BOTTOM: Response to 100 Hz tone-burst stimulus before and after application of TTX to the round window membrane. Measurements made between 3 hours and 18 hours after the application of TTX did not show large variations. 136 1000 Hz Tone Burst Stimulus 0 I I I _ I 0 2 4 1 I · · I 6 10 8 Time (ms) I I I I 12 14 1000 Hz Tone Burst Response 400 300 :L C. O 200 fted +300pV) 100 0 -100 -200 0 2 4 6 8 10 Time (ms) 12 14 Figure A-25: Cat #7. TOP: 1000 Hz tone-burst stimulus at about 110 dB SPL. BOTTOM: Response to 100 Hz tone-burst stimulus before and after application of TTX to the round window membrane. Measurements made between 3 hours and 18 hours after the application of TTX did not show large variations. 137 138 Appendix B Summary of results: Stimulus to one window Data from all single-sided level series measurements are contained within this appendix. There are differences among the experiments (Cats #1 to #7) which are discussed in Appendix A. All of the figures in this appendix have the same layout. * The top left hand plot is the magnitude of the cochlear-potential response as a function of stimulus sound-pressure level for single-sided stimuli at both the oval and round windows. * The top right hand plot is the angle of the cochleax-potentialresponse as a function of stimulus sound-pressure level for stimuli at both the oval and round windows. * The middle left hand plot is the dB difference between the cochlear-potential mag- nitude when the oval window is stimulated and the cochlear-potential magnitude when the round window is stimulated, as a function of stimulus sound-pressure level. This difference is the dB difference between the two responses in the top left hand plot. * The middle right hand plot is the differencein angle between the cochlear-potential angle when the oval window is stimulated and the cochlear-potential angle when the round window is stimulated. This difference is the difference in cycles between the two responses in the top right hand plot. 139 * The lower left hand plot is an estimate of DI where D is obtained from the data in the top two plots and Equation 1.1: VCP = D(Pow - PRW). Here it is assumed that C = 0 and the pressure at the unstimulated window is zero. * The lower right hand plot is an estimate of LD described above. The figures are arranged first in order of increasing frequency. Within each frequency the figures are arranged in chronological order of experimental cat. An attempt was made to keep all axes ranges constant for each group of measurements at a specific frequency. In a few cases this was not practical. When the phase angle plots have different absolute ranges the relative range is constant. 140 100 Hz Cat #1 -80 _ an .DU .25 _ ..o-- OW -100 . >^ 0a, to 0t 0 0 o. -120 xN, .25 _ -140 , I I I I 60 80 100 120 -.50 W I I I 60 80 100 120 80 100 120 -8 oa .66 0 .65 -10 >-0- -- .64 -12 60 80 100 N 120 60 ., 0I o 01 ...... IDI:OW -IDI: RW ........ 0 107 r - D: OW - LD: RW N I 60 . 80 . o........... I ,I , 100 r - - -· .i 120 I- I I I I I I 60 80 100 120 _- Level (dB SPL) Level (dB SPL) Figure B-1: TOP: Single-sided level-series measurements made on Cat #1 at 100 Hz. Either the ovalor the round windowwas stimulated. MIDDLE:Ratio of the measurement made while the oval windowwas stimulated and the measurement made while the round window was stimulated. BOTTOM: Estimate of D (difference-mode gain) from the single-sided level-series measurements. In this estimation it is assumed that CI << IDI. 141 100 Hz Cat #2 -80 _ 1 .50 _ 0 --o-- OW - RW --- noisefloor 'Q -100 _ 25 _ a) 0 >. a) co m a1 20 - 0 >O d 25 _ 1 40 I I I I I I 60 80 100 I I 120 60 I60 1 3 2 0 ",1 00 No 0 0 = -2 a. (. n (,3 03 a3. 60 10 100 100 120 120 0 o 10 -6 n -7 10J 1 80 100 120 80 100 120 .5 .t L A F~ 60 -5 I I 100 r . ,,0CL 80 80 I 80 .5 ------IDI:OW IDI: RW ......-----D: OW - D: RW a, 0 o 0 0 I _- 60 I I 80 II I I 100 120 N -.5 ,,,,,,,, 60 Level (dB SPL) 80 100 120 Level (dB SPL) Figure B-2: TOP: Single-sided level-series measurements made on Cat #2 at 100 Hz. Either the ovalor the round windowwas stimulated. MIDDLE: Ratio of the measurement made while the oval windowwas stimulated and the measurement made while the round window was stimulated. BOTTOM: Estimate of D (difference-mode gain) from the single-sided level-series measurements. In this estimation it is assumed that C << ID1. 142 100 Hz Cat #3 ,--_ .bU -80 _ --o-- OW -&- RW --- -1 0o vv noisefloor .25 - - c, 9> c. 0 a. 0n o -1 20 N " / b '. -.25 i -140 . I .I I 80 100 120 I 30 -.50 I- I I I I 60 80 100 120 m _ n- 0 0 a. 0 0 > - .D .5 _ .- ------------ ------ N 0~ l o 2 -2 0 60 80 100 .> ',4 120 .4 _ 60 I I I 80 100 120 1 ..----- D: OW -D: RW --......IDI:OW 1 05 CZ 0c 1 06 n 1 0' 7 , _ !B 60 I I I 80 100 120 N .5 _ 0 l' 60 Level (dB SPL) 80 100 120 Level (dB SPL) Figure B-3: TOP: Single-sided level-series measurements made on Cat #3 at 100 Hz. Either the oval or the round windowwas stimulated. MIDDLE:Ratio of the measurement made while the oval window was stimulated and the measurement made while the round window was stimulated. BOTTOM: Estimate of D (difference-mode gain) from the single-sided level-series measurements. In this estimation it is assumed that ICI << IDI. 143 100 Hz Cat #4 1.00 -80 _.-o--.OW -&- RW --- noisefloor .75 -1 00 co c) 0 0~ a- a 1 20 a. .50 0 N .25 1 An -Vj 0 ! I I I I I I I 60 80 100 120 60 2 a 80 100 120 .6 n0 0 - --------------- a_ ------ .5 u 0 0 -2 60 9 80 100 N 120 FA - -- - - - - - - - --- a. .4 60 80 100 - - 120 .5 ILI 1 0-5 F I 0 1 0_6 1 0' 7 I 630 ...... ZD: OW - D: RW C3 0 N I 100 120 Level (dB SPL) 80 ;·i 60 _ 60 I I I 80 100 120 Level (dB SPQ) Figure B-4: TOP: Singe-sided level-series measurements made on Cat #4 at 100 Hz. Either the oval or the round windowwas stimulated. MIDDLE:Ratio of the measurement made while the oval windowwas stimulated and the measurement made while the round window was stimulated. BOTTOM: Estimate of D (difference-mode gain) from the single-sided level-series measurements. In this estimation it is assumed that JCJ << ID1.. 144 100 Hz Cat #5 I,, -80 _ .DU - Q!Q --o--OW -A- RW --- noisefloor .25 - 100 b. 0 5a b , 0 'O 0 0 C. -120 N -.25 -140 - - -. 50 I I I . I I I 60 80 100 . I 120 I I [[[ I I I 60 80 100 I~~~ I 120 c 2 r 0 -i -i .6 K o .5 0 _'3 r I i I I I I 60 80 100 120 -f -_ 0 0 .4 II 60 I- I II I I 80 100 120 ; aL .5 5 10 ......-----ID: OW -IDI: RW C, a, 0 ' 0 10 6 <: > 0 ......-----ZD: OW - D: RW 0 1 0-760 C 60 I 80 _I 100 N 120 Level (dB SPL) -. 5 660 .t:O 80 100 120 Level (dB SPL) Figure B-5: TOP: Single-sided level-series measurements made on Cat #5 at 100 Hz. Either the ovalor the round windowwas stimulated. MIDDLE: Ratio of the measurement made while the oval window was stimulated and the measurement made while the round window was stimulated. BOTTOM: Estimate of D (difference-mode gain) from the single-sided level-series measurements. In this estimation it is assumed that ICi << ID. 145 100 Hz Cat #6 .50 -80 -----o--&--- -100 OW Pre-TTX RW Pre-TTX OW Post-TTX RW Post-TTX noisefloor .25 CD) 0> a, a m 0 -Q 0 -120 N -.25 - -140 60 I I I 80 100 120 -.50 60 2I 80 .1( 100 -V - 0I > c _._ C) . 60 (0 U / Pre-TTX - - Post-MX .5 -2 2 80 100 n*3. -- IDI:RWPost-TTX 10 1_ I 60 0 -. I I I 80 100 120 _ _ DaO- _ _- a -3- IDI: OW Post-TTX -_n ,, 10 L_ r 60 120 -.- IDI:OWPre-TTX -- IDI:RWPre-TTX -L.-0 A . 120 I I 80 N o I I I 100 a -.5 C] -1 -- Iffi 60 120 ^.-- LD: OWPre-TTX D: RWPre-TTX \/ - D: OWPost-TTX - LD: RWPost-TTX / l l Il I I 80 100 120 Level (dB SPL) Level (dB SPL) Figure B-6: TOP: Single-sided level-series measurements made on Cat #6 at 100 Hz before and after the application of TTX. Either the oval or the round window was stimulated. MIDDLE: Ratio of the measurement made while the oval window was stimulated and the measurement made while the round windowwas stimulated. BOTTOM: Estimate of D (difference-mode gain) from the single-sided level-series measurements. In this estimation it is assumed that JIC << ID_. 146 100 Hz Cat #7 .50 -80 _ --e-- OW Pre-TTX - RW Pre-TTX --o-- OW Post-TTX -- RW Post-TTX --- noisefloor 100 .25 m) V 00 0 0 > -120 .25 140 a- ! m I I I 60 80 100 .50 1 120 60 V 2 .b Pre-TTX --- Post-TTX a0 - 0 80 o0 - -- - -- - -- - -- .----- -2-2I 1= i i i 60 80 100 120 10 --------------------- .5 .4 o 10 80 100 I 120 _, C') 0 6 -A--.- 0 7 10I 03) IDI:RWPost-TTX 'Zd 10 80 60 .b -a- IDI: OW Post-TTX - -Pre-TTX --- Post-TTX , -. IDI:OWPre-TTX -- IDI: RWPre-TX 5' 120 r 0 00 100 r I I I 60 80 100 120 N -.5 r 60 I ZD: OWPre-TTX ZD: RWPre-TTX ZD: OWPost-TTX ZD: RWPost-TTX I I I 80 100 ! I 120 Level (dB SPL) Level (dB SPL) Figure B-7: TOP: Single-sidedlevel-seriesmeasurements made on Cat #7 at 100 Hz before and after the application of TTX. Either the oval or the round window was stimulated. MIDDLE: Ratio of the measurement made while the oval window was stimulated and the measurement made while the round window was stimulated. BOTTOM: Estimate of D (difference-mode gain) from the single-sided level-series measurements. In this estimation it is assumed that Ct << IDI. 147 170 Hz Cat #4 -80 .75 I--..-- OW ARW po --- noisefloor .50 -100 (0 a) o q) m a tL 25 a: o -120 9~X~~ ----------.. QP. 0 > 0 140 m ! I I I I I 60 80 100 -.25 I 1 120 60 100 120 100 120 1 2 .b _ a 0 0 - -2 > 0cn 1 0 a. o 10 0 .3 o .5 X.- -'A lfl I 60 ES 80 80 5 100 120 0o .4 60 i N · I. I .O 80 _ ...----...IDI: OW ID: RW ------ /D: OW - D: RW w uC C) 0 1 0 - 7 I r_ 60 II I - 80 100 -- II o N 120 -.5 _ 60 Level (dB SPL) 80 100 120 Level (dB SPL) Figure B-8: TOP: Single-sided level-series measurements made on Cat #4 at 170 Hz. Either the ovalor the round windowwas stimulated. MIDDLE:Ratio of the measurement made whilethe oval windowwas stimulated and the measurement made while the round window was stimulated. BOTTOM: Estimate of D (difference-mode gain) from the single-sided level-series measurements. In this estimation it is assumed that ICI << IDl. 148 200 Hz Cat #1 anl .DV -80 _ ..o--OW -A- RW --- noisefloor -100 .2 5 _ - (,i) i0 0 a. 1 20 oC. - ,q -.25 _ -.50 I 1 40 I 60 m .,n e a- ".I I ." 80 - I " I 100 120 I I 60 80 100 120 60 80 100 120 I 1 .6 __ a. >1 0 0 0 .5 a. -2 60 >L 10 ,I IA 80 I 100 120 O ,, .5 ------IDI:OW -IDI: RW 1 0' 6 .. n 7 L~ 60 I ...... ZD: OW D: RW , EDI 10 .4 c 5 co a- I. 0 \i -.5 60 L~ 80 100 120 Level (dB SPL) I I I 80 100 120 Level (dB SPL) Figure B-9: TOP: Single-sided level-series measurements made on Cat #1 at 200 Hz. Either the ovalor the round windowwas stimulated. MIDDLE:Ratio of the measurement made while the oval window was stimulated and the measurement made while the round window was stimulated. BOTTOM: Estimate of D (difference-mode gain) from the single-sided level-series measurements. In this estimation it is assumed that C << ID[. 149 200 Hz Cat #2 ./5 ,= -80 _ --o-- OW --- RW --- noisefloor 50 i _ 100 a) 25 _ co a) - o -120 -- _i - ------ ----- . >l. ,q 0 -140 _ I I I I 60 80 100 120 -.255 ?_ I m 60 80 I I I I 100 120 m 2 1 - .0 -3a 0. 0 ------------------- ---- .5 60 0 10 10 - 0a. .4 -2 0 5 w a 80 100 120 N 5 80 100 120 i ....--. D: OW ZD: RW a, 6 60 ------ _ ......--IDI: OW IDI: RW 1 0-7 1 --- I-6 60 .O --- ---- 0 II 80 -I- II - I 100 I N 120 -. 5 [- 60 Level (dB SPL) I I I 80 100 120 Level (dB SPL) Figure B-10: TOP: Single-sided level-series measurements made on Cat #2 at 200 Hz. Either the oval or the round window was stimulated. MIDDLE: Ratio of the measurement made while the oval window was stimulated and the measurement made while the round window was stimulated. BOTTOM: Estimate of D (difference-mode gain) from the single-sided level-series measurements. In this estimation it is assumed that ICI << IDI. 150 200 Hz Cat #3 -80 _, .Z0 - m --o-- OW 0 1 00 m o "o a. 0 1 20 0 -. 25 m -.50 _ m 1 40 - I.. I 60 . I . I 80 100 I -.755 ' I , 1 II I80 60 120 80 100 I 120 100 120 m 0 2 a: rr .6 0 0 0 0 NC> .5 ------------- I ---------- O - 0 1. o CO -2 .60 , . 80 100 I ...... ID: OW IDI: RW 1 0-5 ,qD_ o .... N A . i - C30 120 i I I 80 100 120 .5 ...... D: OW _- LD: RW 0 an O) o> 1 06 0 1 0-7 60 I I I 80 100 120 0 N o v r~ -.5 660 Level (dB SPL) I I II II 80 100 120 Level (dB SPL) Figure B-11: TOP: Single-sided level-series measurements made on Cat #3 at 200 Hz. Either the ovalor the round windowwas stimulated. MIDDLE: Ratio of the measurement made while the oval window was stimulated and the measurement made while the round window was stimulated. BOTTOM: Estimate of D (difference-mode gain) from the single-sided level-series measurements. In this estimation it is assumed that jIC << IDJ. 151 200 Hz Cat #4 '= -80 ./1 m AI .50 -100 (I, co) <, -o a- -120 - .25 C- \ 0 -140 I I I II I I I 60 80 100 120 60 80 100 120 m I a -O o a 0 - 2-I 0a. co 60 , I 80 -5 100 120 ...... IDI: OW IDI: RW 1u 1 0 N I .4 1- 60 80 100 " v, . I 120 ...... LID: OW ~ z D: RW 0 I r) 10 ------- I .0r 6 :r 5 ------. .5 C 0 0(/ _N m .b 7 i~ 0 io I I I I 80 100 I _ -. 5 120 m 60 Level (dB SPL) 80 100 120 Level (dB SPL) Figure B-12: TOP: Single-sided level-series measurements made on Cat #4 at 200 Hz. Either the ovalor the round windowwas stimulated. MIDDLE: Ratio of the measurement made while the oval windowwas stimulated and the measurement made while the round window was stimulated. BOTTOM: Estimate of D (difference-mode gain) from the single-sided level-series measurements. In this estimation it is assumed that IC << ID. 152 -- -80 250 Hz Cat #4 ./5 - , .- o--OW RW --- noisefloor -100 .50 (I, 0 . co3 (, -120 - 25 _ 0 N Q9 P--Q 0 -140 6 . "- .. '''.''_ .25 7 .' _' I of , I 60 80 100 60 120 2 80 100 1 120 .6 _ - 0 - -----o -------- 0 .4 60 80 100 ----- IDI: OW IDI: RW CO a. :-. 0 53 1 0-7 120 N L H_ __ 60 .o I I\ 80 100 120 _ 1 0-5 1 06 .5 a. F -2 20.3 . .· a, 0 0 a I=. 60 80 100 120 ,q _ . .5 m 60 Level (dB SPL) D: OW --.- I D: RW m I Ii 80 100 120 Level (dB SPL) Figure B-13: TOP: Single-sided level-series measurements made on Cat #4 at 250 Hz. Either the oval or the round windowwas stimulated. MIDDLE: Ratio of the measurement made while the oval windowwas stimulated and the measurement made while the round window was stimulated. BOTTOM: Estimate of D (difference-mode gain) from the single-sided level-series measurements. In this estimation it is assumed that JIC << IDI. 153 300 Hz Cat #5 ./O '-=r -80 _ --o-- OW -A- RW --- noiseflo -100 .50 _ .25 _ _ 0, 0) 5n -o a- 0 -120 a- \l oo 0 Oq Q. -140 _ I 40 I I 60 I 80 I 100 80 100 120 -. 25 I 120 '! I I 40 40 60 t0000 ~ I I I 80 ~~~I I 1 100 120 co A .5 2 a a a - 0 - ----------------- fll%_ - __ - --o. -o r -C r 40 I I 60 80 I I 100 120 0 0 .4 c,_ N 40 .O _ 0C,) 10 -----------------\;r·- .5 5 CO 0- 1 06 ------IDI: OW IDI:RW 1 0-7 I 40 \, N I I 60 80 I 100 120 100 120 ......-----D: OW D: RW 0 m -.5 40 3e I 80 m Cn (d 60 I I 60 80 I I 100 120 Level (dB SPL) Level (dB SPL) Figure B-14: TOP: Single-sided level-series measurements made on Cat #5 at 300 Hz. Either the oval or the round window was stimulated. MIDDLE: Ratio of the measurement made while the oval windowwas stimulated and the measurement made while the round window was stimulated. BOTTOM: Estimate of D (difference-mode gain) from the single-sided level-series measurements. In this estimation it is assumed that CI << IDI. 154 300 Hz Cat #6 -80 .50 -4- OWPre-TTX - RW Pre-TTX .-o-- OW Post-TTX --- RW Post-TTX --- noisefloor -100 .25 m 0a. -120 {- 0 N -.25 140 -.50 40 60 80 100 120 40 2 - ar a. Pre-TTX --- Post-TTX a. i: .b 80 100 120 _ Pre-TTX - _,, Drsv - - - rUOt -- I. 3 .5 0 60 . ----- I IA --- _- 3O .4 -2 40 60 80 N 100 120 F 40 I I I 60 80 100 120 cI 0 0 1 05 o n co a) 0 o 1 06 Z5 1 06 10~ -A- IDi:OW Pre-TrX -- IDI: RWPre-T-X -4o IDI:OW Post-TX -IDI: RWPost-TTX _II I 40 0 N 60 80 .5 _ 100 120 Level (dB SPL) -1 - ZD: L- OWPre-TTX -D: RW Pre-TTX -0- ZD: OWPost-TX - ZO: RWPost-TTX I- ! ! 40 60 80 . ;, I i I i I 100 120 Level (dB SPL) Figure B-15: TOP: Single-sided level-series measurements made on Cat #6 at 300 Hz before and after the application of TTX. Either the oval or the round window was stimulated. MIDDLE: Ratio of the measurement made while the oval window was stimulated and the measurement made while the round window was stimulated. BOTTOM: Estimate of D (difference-mode gain) from the single-sided level-series measurements. In this estimation it is assumedthat ICI << DI. 155 300 Hz Cat #7 .50 -80 --*-- OW Pre-TTX -&-RWPre-TTX --o-- OW Post-TTX -- RW Post-TTX --- noisefloor .25 -1 00 ID, Co a) 0 a) - 0 a_ -1 20 0 0 0 NcJ L -.25 -14C I I 40I 40 2 cr >O 0 - - 0 -2 IL 40 I I I r_ I -. JU 80 100 120 60 80 100 120 F I\ \- . .-- _. 40 0 . .5 ,II a- I 80 .---- >1 I 60 ------ 0 0 I 100 120 . ,4 Y N [ F 40 100 120 Pre-TTX --- Post-TTX i a- / / 80 .5 Pre-TTX --- Post-TTX -- 60 -. .. I I I I I I I I 60 80 I 1 100 120 0 10 -5 (. c( a) 0. co 0 10 10 -6 7 ----4v-B I 40 I ! I 60 ! !I I 80 IDI: OW Pre-TTX IDI: RW Pre-TTX IDI: OW Post-TTX IDI: RW Post-TrX !I I - .5 --- -- -- 0 -1 I !~~~ r 40 100 120 - Q0/ \ I 60 80 ZD: OWPre-TTX D: RW Pre-TTX D: OW Post-TTX LD: RWPost-TTX I I 100 120 Level (dB SPL) Level (dB SPL) Figure B-16: TOP: Single-sided level-series measurements made on Cat #7 at 300 Hz before and after the application of TTX. Either the oval or the round windowwas stimulated. MIDDLE: Ratio of the measurement made while the oval window was stimulated and the measurement made while the round window was stimulated. BOTTOM: Estimate of D (difference-mode gain) from the single-sided level-series measurements. In this estimation it is assumed that ICI << ID1. 156 320 Hz Cat #4 .50 -80 --o- OW RW --- noisefloor .25 _ -100 9 U, 0 a. o -120 o 0 9 - , \:---o-.. o a d "o 'O.. O .25 -140 -.50 60 a 80 100 120 2 ac rc T I I I 60 80 100 120 .6 a. o :> N 0 .5 --------------------------- 0 ----- a L 2 I a. o 60 (o 1 0' 0 (, o > ES 10 1 0' I I I II 80 100 120 I o 4. m-- 60 5 80 100 120 ,..... .b -(6 ------IDI:OW o( 0 N 0 (3 ------ ZD: OW - D: RW r 0 v 60 7 60 I 80 I 100 I -.5 120 t- 60 Level (dB SPL) I 80 I I 100 120 Level (dB SPL) Figure B-17: TOP: Single-sided level-series measurements made on Cat #4 at 320 Hz. Either the ovalor the round windowwas stimulated. MIDDLE:Ratio of the measurement made while the oval window was stimulated and the measurement made while the round window was stimulated. BOTTOM: Estimate of D (difference-mode gain) from the single-sided level-series measurements. In this estimation it is assumed that ICj << DI. 157 400 Hz Cat #4 rn-_ .OU r- -80 _ v v .- o--OW -A RW --- noisefloor .25 00 -1 co 0 Q a 0 a- 0 120 a N 0 .i -. 25 _ a., IO,.> -140 I 60 I"· I I I 80 100 120 ' r- 2 -.50 -I 60 80 I 100 I 120 60 80 100 120 I I I I I I 80 100 120 3 cc a. 0 .5 0. -2 n0 c I I 60 80 I I 100 120 N .4 _. -- : 60 ,,q .5 10-5 o co r 0 'O 0 f_ .0 (0 ......--IDI: OW IDI:RW 1 06 ' I. 1v I _. I ! I I I I 60 80 100 120 r I o - ...... LD: OW ZD: RW 0 a N '.5 60 Level (dB SPL) 80 100 120 Level (dB SPL) Figure B-18: TOP: Single-sided level-series measurements made on Cat #4 at 400 Hz. Either the oval or the round windowwas stimulated. MIDDLE: Ratio of the measurement made while the oval window was stimulated and the measurement made while the round window was stimulated. BOTTOM: Estimate of D (difference-mode gain) from the single-sided level-series measurements. In this estimation it is assumed that CI << D[. 158 500 Hz Cat #4 -80 .50 _ ---- OW -, RW --- noisefloor -100 .25 - m cq a) 'm 0 ;> c a -120 a. 0 d -.25 -140 - "-o -o-o.. - -.50 60 80 100 120 2 -I I I 60 80 100 120 60 80 100 120 .6 a. co 'O : N3: 0 0a. .5 0 o0 .4 -2 a> 0 60 1 cs 1 0 80 100 120 N 5 .5 r...... ZD: OW - D: RW 0) o- a, 1 10 0 ...... IDI: OW -ID: RW -7 - 60 I I I 80 100 120 I I I 0 N Level (dB SPL) -.5 !1 I .......... I 60 80 100 ... I 120 Level (dB SPL) Figure B-19: TOP: Single-sided level-series measurements made on Cat #4 at 500 Hz. Either the oval or the round windowwasstimulated. MIDDLE: Ratio of the measurement made while the oval window was stimulated and the measurement made while the round window was stimulated. BOTTOM: Estimate of D (difference-mode gain) from the single-sided level-series measurements. In this estimation it is assumed that CI << IDI. 159 600 Hz Cat #1 -80 -100 In _ _ .DU m .25 _ _ 2 -c 0 0tO _ 0 -120 a ,q .b .25 1 40 _ q 'b-0--0-0-,0---0.,..0- - 6 I 60 80 -. 50 1 1 100 120 I I . I . I . I 60 80 100 120 I I . 80 100 120 m .6 2 a. -0. a .5 UI -2 I o I1 60 0 10 I 80 I 100 120 -5 .4 -I 60 .5 0 O > ,, .------ D: OW D: RW 0Cn 10 6 0 ...... IDI:OW -DI: RW ES 1 0 7 0 N 60 80 100 120 Level (dB SPL) 0 -.5 I I I I 60 80 100 120 Level (dB SPL) Figure B-20: TOP: Single-sided level-series measurements made on Cat #1 at 600 Hz. Either the oval or the round windowwas stimulated. MIDDLE:Ratio of the measurement made while the oval window was stimulated and the measurement made while the round window was stimulated. BOTTOM: Estimate of D (difference-mode gain) from the single-sided level-series measurements. In this estimation it is assumed that JIC<< ID. 160 600 Hz Cat #2 -- .bU -80 --o-- OW -- RW --- noisefloor .25 100 a 0 t_ r -i v 0 a. 0 -120 v (. N -.25 40 1 'o - I I I I I I I 80 100 120 I 60 -.50 - I 60 I I 80 I I 1I 100 120 m -13 2 .6 0 ----------- >c ----------- -co . 0 -2 a. -1 I 60 o .5 - ...... 10 I I I l I I I-- 80 100 120 N .4 4_ 60 60 \4 5 I .;) 80 80 100 120 100 120 I-- CD 0 o 10 10 ------IDI:OW IDI:RW 7 I .l I I ! I 60 80 100 120 ----- LD: OW -LD: RW 0 0 N \4 -.5 _1 60 Level (dB SPL) I I I 80 100 120 Level (dB SPL) Figure B-21: TOP: Single-sided level-series measurements made on Cat #2 at 600 Hz. Either the ovalor the round windowwas stimulated. MIDDLE: Ratio of the measurement made while the oval window was stimulated and the measurement made while the round window was stimulated. BOTTOM: Estimate of D (difference-mode gain) from the single-sided level-series measurements. In this estimation it is assumed that ICI << IDI. 161 ----------- ·---------·----- ·- ·---- ------- ·------------ --- 600 Hz Cat #3 _ 1 -80 .DV -o-- OW RW --- noisefloor -1 w _ .25 _ 00 CO c- 0 m 'a 0 a- 0 120 a. o N ,q Q .25 _ 1 40 - '. I I I I 60 80 100 120 -_rio -. 50 - 2 I ! I 80 100 120 1 60 1 0 :' 0 .6 0 -2 - .5 -1 60 I 80 I I 100 120 > 0 .4 N 5 1 60 60 1 .0i 80 100 ......- D: OW D: RW , 1 06 1. -7_ 120 .5 c) 5ni 1 a. a: 0co -I -I ...... ID: OW -IDI: RW _, ~: 60 ii ! I I 80 100 120 v N 0 .5 60 Level (dB SPL) I I I 80 100 120 Level (dB SPL) Figure B-22: TOP: Single-sided level-series measurements made on Cat #3 at 600 Hz. Either the oval or the round window was stimulated. MIDDLE: Ratio of the measurement made while the oval window was stimulated and the measurement made while the round window was stimulated. BOTTOM: Estimate of D (difference-mode gain) from the single-sided level-series measurements. In this estimation it is assumed that ICI << ID}. 162 600 Hz Cat #4 .50 -80 .25 1 00 I 0 0 a1. -p C,q N" o -1 20 a -.25 -140 _ I I I I 60 80 100 120 -.50 60 80 100 120 60 80 100 120 03 2 .6 o >1 0 0 - o 0 0- -2 O 60 80 100 N 120 .5 .4 .5 1 0- o 10 6 10 7 _ r-' W a, [:: v i ~ I I 60 80 ~ 0 ------IDI: OW IDI: RW 0 ~~~~~~~~~~~~~~~III N I I 100 120 ......-----D: OW D: RW - - Z -.5 -- 60 Level (dB SPL) .' 80 ~ 100 -' - I 120 Level (dB SPL) Figure B-23: TOP: Single-sided level-series measurements made on Cat #4 at 600 Hz. Either the oval or the round windowwas stimulated. MIDDLE:Ratio of the measurement made while the oval windowwas stimulated and the measurement made while the round window was stimulated. BOTTOM: Estimate of D (difference-mode gain) from the single-sided level-series measurements. In this estimation it is assumed that CI << IDI. 163 800 Hz Cat #1 _, .bU -80 _ .25 _ 1 00 - c) a) (. 0 i_ -n - 1 20 0 N - Q _. -. 25 -1401 a - 60 80 100 I 60 80 100 120 o-do--o-o--"-c- -. 50 2 _, -o- I I , , I 60 80 100 120 I I .tO > oN 0 .5 - -------- ------------- a. 4 - 60 10 aco ES 10 10 - 80 100 120 N - - .I 60 5 ------IDI: OW IDI: RW _ 7 ! 60 80 0 I I 80 100 120 ------ /D: OW ZD: RW I--.................. _-- ..... 5 0 . 100 I I ~~1 . 1 -6 _ I I 3 120 60 Level (dB SPL) I !...I Al 80 100 120 Level (dB SPL) Figure B-24: TOP: Single-sided level-series measurements made on Cat #1 at 800 Hz. Either the ovalor the round windowwas stimulated. MIDDLE:Ratio of the measurement made while the oval windowwas stimulated and the measurement made while the round window was stimulated. BOTTOM: Estimate of D (difference-mode gain) from the single-sided level-series measurements. In this estimation it is assumed that IC << IDI. 164 800 Hz Cat #2 7^ -80 / _ -..o-- OW -i-RW --- noisefloor 1 00 .oo-o-. .50 _ *0 _ a) Io pd 1 0 20 _ .25 >a d _ 0 0 -140 _ 60 60 80 100 120 80 100 120 -. 25 m! I *_ * I I I I 60 80 100 120 I I I I I ! 80 100 120 m - .or"_ 2 0o Q_ o .5 UI a- 0 o a -IleI 60 CZ 10 I II Ia 80 100 120 _ o .4 - N -5 III .... I 60 1 --- eC ------ /D: OW ZD: RW 1 Q) o0 a) 1 0 '6 0 ...... IDI:OW IDI:RW 10 7 I 60 80 Level I II 100 120 .5 0 _- a N 0 -! _,1 I 60 (dB SPL) I. I. IB 80 100 120 I Ii Level (dB SPL) Figure B-25: TOP: Single-sided level-series measurements made on Cat #2 at 800 Hz. Either the ovalor the round windowwasstimulated. MIDDLE: Ratio of the measurement made while the oval windowwas stimulated and the measurement made while the round window was stimulated. BOTTOM: Estimate of D (difference-mode gain) from the single-sided level-series measurements. In this estimation it is assumed that JCI<< ID. 165 800 Hz Cat #3 ./t _ ., CQb _ -oU -o--OW &- RW --- noisefloor .50 00 -1 (/ ra) v .25 a -o -120 a. O) N OI 0 -140 V 0 I l I I 60 80 100 120 -.25 2 - - a I I I I 60 80 100 120 r- a .0 0 .5 ---------- a: 0o o - --------------------- -v -a. N0 2 n n- .2 I 60 10 o0 1 0 II 80 I 100 120 O . 4. -I 0 V 5- I I I I I I 60 80 100 120 1 ------ ZD: OW LD: RW (C 6 _ - 10 I > 7 _ --...... IDI: OW IDI: RW I I I I I I I 60 80 100 120 0 5 0 N N & 60 Level (dB SPL) I I I I I I 80 100 120 Level (dB SPL) Figure B-26: TOP: Single-sided level-series measurements made on Cat #3 at 800 Hz. Either the oval or the round windowwas stimulated. MIDDLE:Ratio of the measurement made while the oval window was stimulated and the measurement made while the round window was stimulated. BOTTOM: Estimate of D (difference-mode gain) from the single-sided level-series measurements. In this estimation it is assumed that CI << D1. 166 800 Hz Cat #4 nn 1 .UU -80 --o.- OW -&- RW --- noisefloor 0..D .75 'a -100 (> co 0 a.50 0o a o -120 .25 -140 - ,..o..O 0 60 80 100 120 60 r- -o 2 -------- I .5 0 -2 I a. 0co 10 Cu a0 10 5 120 0 - > 100 r' .t a. 80 10 !I I I I I I 60 80 100 120 A > N -5_ v . LI I I I 80 100 120 I I 60 I 1 I ----- ZD: OW ZLD: RW a, 6 ------IDI: OW -IDI: RW 7 60 I I I 80 100 120 o .5 I v CD 0 0 N 0 -l 60 Level (dB SPL) I I I 80 100 120 Level (dB SPL) Figure B-27: TOP: Single-sided level-series measurements made on Cat #4 at 800 Hz. Either the ovalor the round windowwas stimulated. MIDDLE: Ratio of the measurement made while the oval windowwas stimulated and the measurement made while the round window was stimulated. BOTTOM: Estimate of D (difference-mode gain) from the single-sided level-series measurements. In this estimation it is assumed that KCI << ID1. 167 1000 Hz Cat #1 -r / _ 0 -80 _ 50 _ .-o-- OW -*- RW -1 00 --- _ 6-.0.0-0-0--0-0-- nois co a) -o v a .25 _ -120 > ,q 1 40 0 ,---------- -160 I I I 40 m co l I 80 -.25' lI I~~~~~ I 120 c I I 40 80 120 40 80 120 - I I .55 I. 0 .5 'a-o 0 0 22 -14 40 -i0 0 10 4 0- 10 5 80 120 ~q .0 ......---IDI: OW IDI: RW 0 0co > .45 I I (1) - 0 5 E> LD: OWI D: RW r 1 06 I 40 -.5 I I 80 -- II =_ 40 1 20 : i J : I '_ 80 _- L 120 Level (dB SPL) Level (dB SPL) Figure B-28: TOP: Single-sided level-series measurements made on Cat #1 at 1000 Hz. Either the oval or the round window was stimulated. MIDDLE: Ratio of the measurement made while the oval window was stimulated and the measurement made while the round window was stimulated. BOTTOM: Estimate of D (difference-mode gain) from the single-sided level-series measurements. In this estimation it is assumed that Cj << ID1. 168 1000 Hz Cat #2 r'-f_ .DU pro,oooo 9 -80 > --o-- OW - RW --- nois .25 -100 u, a- o _ - - -- - - / 0 -120 1 > k N d -. 25 -140 -.50 -1 an vv I 40 I ·I 120 40 I I ·I ! 80 : iI ·! !I !I 80 120 80 120 .bb Cr 1- 0 > 0 '- o a. 0 - cci -I. -2 I _ 40 10i' 6 1{¥ . v I _> 4S . . 80 120 .,, N I _ I ' 40 I 80 7~~ . 40 -_:O .3 ------IDi: OW ID: RW C) oQ- -1 5 - 10 0 _ I I ......-----D: OW - D: RW a) o 0 -N _ I rv 120 I I 40 Level (dB SPL) . I I . 80 I I 120 Level (dB SPL) Figure B-29: TOP: Single-sided level-series measurements made on Cat #2 at 1000 Hz. Either the oval or the round window was stimulated. MIDDLE: Ratio of the measurement made while the oval window was stimulated and the measurement made while the round window was stimulated. BOTTOM: Estimate of D (difference-mode gain) from the single-sided level-series measurements. In this estimation it is assumed that IC << IDl. 169 1000 Hz Cat #3 0 -80 _ --o-- OW -A- -.25 _ RW --- noise 100 _ Cal 0 rQ 1 20 -.50 .=1 -------------------------------- I . 40 m Q . o-o44°-ve- -.75 _ I I 80 , I 120 -1.00 I - I 40 I 80 I 120 .55 2 a a. 0 .5 0 0 _F 0 I -2 j _ I 40 80 J > .45 L N 120 104 . I *I 80 i. |~! 120 1 r ----- iDI: OW IDI: RW co .5 r 10 _* 40 1 0-5 5 _ ao _ -160 - -0 o 0 -d , -1 40 a. * I D t 6 0 40 ----......D: OW D: RW 80 II 1- ; 40 120 I I 80 120 I Level (dB SPL) Level (dB SPL) Figure B-30: TOP: Single-sided level-series measurements made on Cat #3 at 1000 Hz. Either the oval or the round window was stimulated. MIDDLE: Ratio of the measurement made while the oval window was stimulated and the measurement made while the round window was stimulated. BOTTOM: Estimate of D (difference-mode gain) from the single-sided level-series measurements. In this estimation it is assumed that IC_<< DJl. 170 1000 Hz Cat #4 .25 -80 --..- OW -4- RW --- noisefloor 0 1 00 (o) a) r p -.25 a 1 20 o a0 N -.50 -140 t)VU - -I J&0--0-00-0 I 40 m I I . 80 0.1 CLa -.75 I 120 80 40 120 l _ ~= .5' 5 _r-L - 5 >o q 40 0 10 80 120 4 Co 0 10 10 , I I I I I ' . 40 80 120 1 ......---IDI: OW IDI: RW C 25 0 >.4! N -2 - ---------- a) 5 - 0 v .5 ...... LD: OW D: RW 0 6 N ~ 40 0 80 120 _ 40 Level (dB SPL) I· I I 80 I 120 Level (dB SPL) Figure B-31: TOP: Single-sidedlevel-series measurements made on Cat #4 at 1000 Hz. Either the oval or the round window was stimulated. MIDDLE: Ratio of the measurement made while the oval window was stimulated and the measurement made while the round window was stimulated. BOTTOM: Estimate of D (difference-mode gain) from the single-sided level-series measurements. In this estimation it is assumed that ICI<< DI. 171 1000 Hz Cat #5 ./0 I- -80 _ 1 00 rn --o-- OW --- RW --- noisefloor 0 _ a, -.25 _ m -1 20 -a. o a _ N" 1 40 -.50 _ I 160 I 40 I I I 80 -. 75 I~~~~~~~~~ I I l I 40 120 120 80 .5 5 r-_ 2 V - I ra -a. o 0 oP 0 0. - 1 0 5 I I 40 80 2 · - - - - - - - - - - - - - - - - - - - - >a. .4[5 -_ 4,I I 0 120 4 ......----IDI:OW IDI:RW I 40 1 0co +- 1 0 - 80I I 120 80 120 ...... /D: OW D: RW a) 0 5 :L N 1 06 40 80 o.5 !I 40 120 I 80 I 120 Level (dB SPL) Level (dB SPL) Figure B-32: TOP: Single-sided level-series measurements made on Cat #5 at 1000 Hz. Either the oval or the round window was stimulated. MIDDLE: Ratio of the measurement made while the oval window was stimulated and the measurement made while the round window was stimulated. BOTTOM: Estimate of D (difference-mode gain) from the single-sided level-series measurements. In this estimation it is assumed that ICK << IDI. 172 1000 Hz Cat #6 .25 -80 --*-- OW Pre-TTX -- RW Pre-TTX --o-- OW Post-TTX -&- RW Post-TTX _ A-,,. --- noisefloor 0 1 00 _ oa, o -. 25 m 1 20 _ 00 1 40 0 -.50 :0 - -160 I I . ! 40 I I I 80 80 120 -.75 II 6, I I I , 40 120 El , 80 I 120 oCr .55 2 a o a- 0 0 0 -2 a_ -- - - -' . I 0 ---------- I 40 N4 0 0 Pre-TTX --- Post-TTX I 120 80 N .45 6 ---a- Pre-TX --- Post-TTX I II ;I_ 40 Pre-TTX 80 1 20 h -U A:64 1 06 -- 1 0 10 - ----- 4-- ,o q 1 04 0 .5 a, .5 IDI:OWPre-TTX IDi:RWPre-TTX IDI:OWPost-TTX IDI:RWPost-TTX 0 CD I I 40 80 I 0 I -Z- ZD: OWPre-TrX -- ZD: RWPre-TTX -a- ZD: OW Post-TTX D: RW Post-TTX -[ 40 120 . . I 80 II I 1 20 Level (dB SPL) Level (dB SPL) Figure B-33: TOP: Single-sided level-series measurements made on Cat #6 at 1000 Hz before and after the application of TTX. Either the oval or the round windowwas stimulated. MIDDLE: Ratio of the measurement made while the oval window was stimulated and the measurement made while the round window was stimulated. BOTTOM: Estimate of D (difference-mode gain) from the single-sided level-series measurements. In this estimation it is assumed that CJ << DI. 173 1000 Hz Cat #7 r .zb --.-- OW Pre-TTX A RW Pre-TTX --o-- OW Post-TTX -- RW Post-TTX --- noisefloor -80 -1 0 00 co 1- -.25 0 0 -1 _ 0- 20 0 4 -. 50 _ -140 ... AV"" . .. , .~------ ii 160 _ , I : 40 I -. 75 . a i Z I I 40 80 ; 120 80 CO I 1 120 .55 I" - ----- .5 0 o -Pre-TTX 0o -.- Post-TTX - a. 9 - o: 1 04 I . I I 40 80 I ' -- IDI: RW Pre-TTX - IDI: RW Post-TTX - N 120 Pre-TTX -.- Post-TTX > .45 i i I _ 40 I I . . I I 120 80 1 -&- IDI:OWPre-TrX 0 ao \X -a- IDI:OW Post-TTX 105 v .5 c) N 10 6 _ I 40 I I 80 0 I 120 Level (dB SPL) -*- ZD:OWPre-TTX -- ZD: RWPre-TrX -.- ZD:OWPost-TrX D: RWPost-TrX -i I 40 80 . I 120 Level (dB SPL) Figure B-34: TOP: Single-sided level-series measurements made on Cat #7 at 1000 Hz before and after the application of TTX. Either the ovalor the round window was stimulated. MIDDLE: Ratio of the measurement made while the oval window was stimulated and the measurement made while the round window was stimulated. BOTTOM: Estimate of D (difference-mode gain) from the single-sided level-series measurements. In this estimation it is assumed that C <«< DL. 174 Appendix C Summary of results: Stimuli to both windows Data from all simultaneous-stimuli measurements are contained within this appendix. There are differences in each of the experiments (Cats #1 to #7) which are further discussed in Appendix A; in general the results from Cats #1, #2, and #3 are not as accurate as the results from the later cats. The figures in this appendix compare the cochlear-potential magnitude and angle measurements with model predictions. Each measurement set has three graphs associated with it; a cochlear-potential magnitude plot, a blow-up of the cochlear-potential magnitude plot around = 0, 0 and a cochlear-potential angle plot. Data points are rep- resented with open circles and the model fits are drawn with solid (linear fit) and dashed (logarithmic fit) lines. The description "linear fit" refers to the model fit obtained from Equation 3.4 and the description "logarithmic fit" refers to the model fit obtained from Equation 3.14. The figures in this appendix are organized in order of increasing frequency. Within 175 each frequency group the figures are arranged in chronological order of experiment by cat number. Measurement sets from a given cat at a given frequency are arranged in order of increasing sound-pressure level. Each measurement set has a label which describes the measurement frequency, cat number, and measurement order on the particular cat; for example, measurement set 1000a_5 refers to the first measurement set made on Cat #5 at 1000Hz. There are two tables for each frequency group within this appendix. The tables give model parameters for all measurement sets for the linear and logarithmic model fits. 176 Data set 75a4 7b-4 dB SPL 124 120 CMRR 24.52 30.83 IDI 1.95e-07 2.04e-07 Linear model parameters: 75 Hz D Icl C PMAG 0.181 1.16e-08 -0.090 0.917 0.227 5.88e-09 -0.192 0.751 P/ 0.573 0.739 MIN Data 0.0035 -0.0136 f'MIN Model 0.0097 0.0027 Table C.1: Linear model parameters calculated from 75 Hz data. Data set 75a4 75b_4 dB SPL 124 120 CMRR | DI 22.20 2.72e-07 28.12 3.04e-07 Logarithmic model parameters: 75 Hz ID IC C PMAG 0.321 2.11e-08 0.036 0.979 0.321 1.19e-08 0.462 0.915 PI P 0.884 0.873 MIN Data |MIN Model 0.0035 0.0125 -0.0136 -0.0046 Table C.2: Logarithmic model parameters calculated from 75 Hz data. IVcpl (dB re 1V) -80 lVcpl -80 - o Data points o Noisy data points -Linear fit -100 fit -100 _ --- Logarithmic -120 0 -0, -120 -0 .......S_ ....3...... -140 -140 - -0.5 0 I . I -80 -80 -1 00 -100 -120 -120 -140 -140 0 0.5 I I ' 0.02 0.5 0 0 -0.5 -o P0 0.5 I UV (cycles) ! .' 1.0 1.0 I · -0.5 I -0.02 0 0.5 ZVcp (cycles) (dB re 1 V) I o I -0.02 0 V . I I 0.02 (cycles) 0 I -0.5 l l l. ' .l l 0.5 -~B~c l l l 0 l l l 0.5 V (cycles) Figure C-1: Simultaneous-stimuli measurement sets and model fits at 75 Hz on Cat #4. 177 Data set 100a_4 100b-4 100a..5 100b_5 100c.5 100d-5 100a_6 100b..6 100c_6 100d_6 100e_6 100f-6 100g_6 100h_6 100i_6 100a_7 100b_7 100c_7 100d_7 100e7 100_7 100g-7 dB SPL 121 120 118 124 120 125 121 126 121 126 116 116 100 110 121 119 127 102 126 118 108 98 CMRR 26.96 32.92 33.24 29.25 21.56 24.81 33.57 20.06 32.11 33.59 32.23 34.66 34.25 32.26 47.71 30.71 52.50 27.60 33.36 23.24 53.81 41.34 DI 3.97e.07 3.97e-07 1.26e-06 1.56e-06 7.29e-07 8.37e-07 1.81e-06 1.12e-06 1.86e-06 2.02e-06 1.68e-06 1.71e-06 1.56e-06 1.81e-06 1.85e-06 1.01e-06 1.17e-06 6.72e-07 1.19e-06 1.23e-06 1.06e-06 1.03e-06 Linear model parameters:100 Hz LD ICI C PMAG 1.78e-08 0.480 0.989 0.037 0.033 8.96e-09 0.371 0.812 -0.030 2.73e-08 -0.097 0.914 0.960 -0.094 5.38e-08 0.474 0.051 6.10e-08 0.271 0.843 -0.007 4.81e-08 0.347 0.982 -0.036 3.80e-08 0.421 0.978 0.841 -0.077 1.lle-07 0.268 -0.039 4.62e-08 0.297 0.965 0.967 -0.074 4.22e-08 0.447 -0.010 4.11e-08 0.232 0.972 -0.011 3.16e-08 -0.123 0.974 0.915 -0.042 3.03e-08 0.246 -0.008 4.41e-08 0.279 0.979 0.972 -0.036 7.60e-09 0.088 0.065 2.93e-08 0.206 0.985 -0.010 2.77e-09 0.271 0.975 0.117 2.80e-08 -0.419 0.970 -0.038 2.55e-08 0.152 0.985 8.47e-08 0.051 0.985 0.015 0.118 2.16e-09 0.307 0.998 0.098 8.83e-09 -0.302 0.991 PI 0.766 0.539 0.970 0.974 0.968 0.924 0.770 0.944 0.915 0.980 0.707 0.993 0.839 0.941 0.985 0.972 0.907 0.997 0.905 0.954 0.985 0.995 MIN Data -0.0047 0.0024 -0.0270 -0.0088 -0.0014 -0.0002 0.0000 0.0038 -0.0004 0.0011 -0.0027 0.0007 -0.0114 -0.0058 -0.0009 -0.0196 0.0047 0.1580 0.0071 -0.0110 -0.0426 0.1341 bMIN Model -0.0024 -0.0037 0.0018 0.0055 -0.0134 -0.0075 -0.0017 -0.0133 -0.0033 0.0001 -0.0028 0.0017 -0.0032 -0.0038 -0.0009 -0.0035 -0.0001 -0.0018 -0.0030 -0.0113 -0.0006 0.0006 Table C.3: Linear model parameters calculated from 100 Hz data. Logarithmicmodel parameters: 100 Hz Data set 100a_4 100b_4 100a.5 100b..5 100c.5 100d..5 100a-6 100b-6 100c.6 100d_6 100e_6 100f-6 100g_6 100h_6 100i_6 100a_7 100b_7 100c_7 100d_7 100e_7 100f_7 100g_7 dB SPL 121 120 118 124 120 125 121 126 121 126 116 116 100 110 121 119 127 102 126 118 108 98 CMRR 4.94 24.07 20.68 45.06 12.23 14.23 21.78 24.78 29.59 31.89 29.19 37.33 26.87 32.19 48.34 32.14 52.22 27.60 31.27 27.79 53.68 26.93 JID 2.67e-07 5.95e-07 1.18e-06 1.39e-06 6.88e-07 7.34e-07 1.00e-06 9.70e-07 1.45e-06 1.54e-06 1.21e-06 1.32e-06 1.31e-06 1.65e-06 1.38e-06 9.05e-07 9.62e-07 6.72e-07 1.14e-06 1.12e-06 1.05e-06 1.02e-06 LD 0.042 0.037 -0.037 -0.090 0.038 -0.002 -0.025 -0.086 -0.042 -0.073 -0.005 -0.037 -0.049 -0.007 -0.044 0.101 -0.000 0.117 -0.040 0.021 0.117 0.100 ICI 1.51e-07 3.72e-08 1.09e-07 7.78e-09 1.68e-07 1.43e-07 8.18e-08 5.60e-08 4.79e-08 3.92e-08 4.21e-08 1.79e-08 5.94e-08 4.07e-08 5.27e-09 2.24e-08 2.36e-09 2.80e-08 3.11e-08 4.59e-08 2.17e-09 4.61e-08 LC -0.269 0.243 -0.002 0.180 0.180 0.172 0.158 0.292 0.296 0.449 0.210 -0.148 0.033 0.205 0.287 0.212 0.436 .0.440 0.068 0.058 0.309 -0.308 PMAG 0.741 0.867 0.948 0.972 0.946 0.947 0.893 0.923 0.974 0.980 0.975 0.994 0.966 0.979 0.980 0.992 0.984 0.969 0.990 0.989 0.998 0.991 /Z 0.298 0.756 0.973 0.973 0.972 0.967 0.720 0.953 0.927 0.980 0.653 0.996 0.820 0.907 0.975 0.983 0.923 0.997 0.903 0.962 0.985 0.994 OMIN Data -0.0047 0.0024 -0.0270 -0.0088 -0.0014 -0.0002 0.0000 0.0038 -0.0004 0.0011 -0.0027 0.0007 -0.0114 -0.0058 -0.0009 -0.0196 0.0047 0.1580 0.0071 -0.0110 -0.0426 0.1341 OMIN Model 0.0827 -0.0094 -0.0030 -0.0008 -0.0303 -0.0275 -0.0116 -0.0064 -0.0052 0.0001 -0.0057 0.0014 -0.0032 -0.0038 -0.0009 -0.0025 -0.0001 -0.0019 -0.0030 -0.0113 -0.0006 0.0036 Table C.4: Logarithmic model parameters calculated from 100 Hz data. 178 ZVcp (cycles) IVcpl (dB re 1 V) IVcpl (dB re 1 V) -8( -80 -10( -100 o Data points e Noisy data points Linear fit --- Logarithmic fit 1.0 -! 0.5 -12( ................ ....... .................. -14C D - noisefloor 100b_4. 120 dB SPL -120 -~ -0 00C. _~~ -140 I " -0.5 0 0.5 0 -0.01 0 | 0 0.01 . ; l~ ~ l l lZ 0 -0.5 0.5 - 1.0 -80 - -10C3l-O -100 - -12( -120 -8C o 0.5 I D)~~ -14C 100a_4 121 dBSPL -140 ~1 . .. -0.5 0 Ni (cycles) 0.5 -0.01 . .. 0 i (cycles) . .. I .. 0.01 0 =. -0.5 . . . . . . 0 . 0.5 I (cycles) Figure C-2: Simultaneous-stimuli measurement sets and model fits at 100 Hz on Cat #4. 179 -80 I- -80 -100 -120 o Data points o Noisy data points Linear fit --- Logarithmic fit - -100 ................. noisefloor ................ I 100a_5 LVcp (cycles) IVcpl (db re 1 V) IVcpI (db re 1 V) ato 0.5 0 -120 118 dB SPL -140 -140 oI . - - - - - -0.5 II - - l - 0 lII 1 0 0.05 II 0.5 -0.05 -0.5 -0.5 0 0.5 0 0.5 0 0.5 0.5 -80 -80 -100 -100 -120 -120 -140 -140 -0.5 0 0.5 _ 0.. i I I. . I' .. -0.05 ' I, ** I 0 .. 0 -0.5 -0.5 0.05 0.5 -80 -80 -100 -100 .................... ......... -120 ...... 1004dBSPL5 124 dB SPL -140 -120 _- .i.. ....... 0 1. . . ........ ... -140 · I -0.5 0.5 0 I 0 -0.05 , 1 0.05 -0.5 -0.5 0.5 -80 -80 -100 -100 50000 _ I II 0 -120 -120 1OOd 5 I 125 dB SPL -140 . -0.5 -140 . . . . .. 0 yI (cycles) I I 0.5 I -0.05 I * I 0 0.05 NM(cycles) -0.5 .9. -0.5 . ... . . . . .... . 0 . . I I 0.5 Ir(cycles) Figure C-3: Simultaneous-stimuli measurement sets and model fits at 100 Hz on Cat #5. 180 ZVcp (cycles) IVcpl (dB re 1V) IVcpl (dB re 1V) 0 ~~~~~~~~~~~~~~~~~~I - -80 -80 -100 -100 -120 -120 -140 -140 o Data points -- Linear fit ---- Logarithmic fit f i oDa'a"°n' !~P-3 I I -0.5 0 0.5 -0.02 0.02 0 A -0.5 -1.0 r....;...... I-0.5 -0.5 · · · 0 II I I 0 0.5 U 0000 -80 -80 _ -100 -100 -120 -120 100b_6 126 dB SPL -140 -140 01111 11111 -0.5 0 r (cycles) 0.5 -o~ 0 0 .................................. 1I , -0.5 · I a -0.02 0.- 0 V (cycles) . I 0.02 -1.0 r,.. I.., I -0.5 II 0 I 0.5 yx (cycles) Figure C-4: Pre-TTX simultaneous-stimuli measurement sets and model fits at 100 Hz on Cat #6. 181 ZV,p (cycles) IVcpl (dB re 1V) 1Vcp1(dB re V) _ p U -80 __ ints 100 -1 120 100g 6 100 dB SPL noisefloor -140 t I -0.5 meet -1 .I". 4- -1 - -.- -0.5 - - - 0 - -- . - . 0 - 0.5.I 0.5 -0.02 0 0.02 -1.0 - -0.5 0 -80 -80 -100 I -120 -120 -140 -140 0.5 0 0.5 m I I -0.5 - 0 lI II - - - I- -100 -0.5 II I - -0.02 I I . I I ! 0 0.02 II -1.0- . -0.5 T . . . . . 0 0 . . I 0.5 I -80 _ -80 I -100 -100 -120 -120 -140 -140 -4 - -0.5 ~a~-~p ~9~r i·"" I I -1.0 . 0 0.5 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~I 4 I- · -0.5 4 - -0.02 0 0.02 * - . - - . . I I I i 0.5 0 0..5 -1.0 -0.5 0 0.5 0 -80 -80 I- -100 -100 -120 -120 -140 -140 I- -0.5 - i -0.5 0 v (cycles) 0.5 i -0.02 i 0 B i 0.02 ,v(cycles) v (cycles) Figure C-5: Post-TTX simultaneous-stimuli measurement sets and model fits at 100 Hz on Cat #6. 182 -/Vc(cycles) IVcpl (dB re 1V) IVcpl (dB re 1V) o -80 I -80 o --- -100 -100 -120 -120 Data points Linear fit Logarithmic fit -0.5 0- -140 100c_6 noisefloor _.............. .............................. ------ --- ----- --- -- -140 I -0.5 I 1 I I 0 0.5 -0.02 0 II . -1.0 0.02 -0.5 0 0.5 ,\ U -80 -80 _ -100 -100 _ -120 -120 -140 -140 i .,,,,,,,y, ............. 0 0.5 ,....... I I -C3.5 2J -0.5 I -0.02 II . 0 -1.0 0.02 - - - · l -0.5 I I .II . -- - 1 0 0.5 0 -80 -80 -100 -100 -120 =-140 ~ _- V100d 6 126 dB SPL --- -0.5 - VF(cycles) 0.5 - -0.5 -120 _..I.............................. I I ---. 0 0- -140 ........................................... ~I - I· | - -0.02 I 0 vy I -. (cycles) 0.02 -1.0 I. I I -0.5 - . . I . 0 . .I- . -A I 0.5 4y (cycles) Figure C-6: Post-TTX simultaneous-stimuli measurement sets and model fits at 100 Hz on Cat #6. 183 0.0 r -80 100 -120 ZVcp (cycles) IVcpl (dB re 1 V) IVcp, (dB re 1 V) -80 I- .. ,. .... 100c_7 102 dB SPL -140 ~·... i . . -100 - -120 -0.5 . I . . . -140 . _ O_I . ---.--_I 0 I I 0.5 -0.02 . -0.5 ..................................... .. . .e......I . . . I . o Data points o Noisy data points Linear fit - - Loganrithmicfit - I 0 -1.0 -0.5 0.02 0 0.5 0.0 -80 -80 -100 -100 I- -120 -120 _ -0.5 * 100a7 -140 S 119dBSPL I:.::.:I:'::: -0.5 -140 ............... 1 - . 0.5 I , ........ . .. tI ; 0 0 2. -0.02 0 0.02 1. -1.0 . . -0.5 : . .' .' I I 0 0.5 0 0.5 0.0 -80 -80 -100 -100 -120 -120 -140 -140 -0.5 -1.0 -0.5 0 xV (cycles) 0.5 -0.02 0 xV (cycles) 0.02 -0.5 V (cycles) Figure C-7: Pre-TTX simultaneous-stimuli measurement sets and model fits at 100 Hz on Cat #7. 184 IVcpl (dB re 1 V) o Data points -80 -80 -100 -120 ...-..... · d_7PL 140 2 a * a i -0.5 -80 -0.5 -120 .AtX oisefloor -140 0.0 - Noisy data points Linear fit --- Logarithmic fit - 100 ZVcp (cycles) IVcpI (dB re 1 V) ! 0 I 1 1 1 0.5 -0.02 0 0.02 -100 -100 4""B -120 I1 -_ -140 I 000,0 I -0.5 00f7 108 dB SPL ' 0 . -120 -100 -100 -120 -120 -140 -140 0 0.02 0.5 ' .. I I · 0 l -1.0 -0.5 0.02 0.0 -80 -100 -100 -120 -120 _ lira -0.5 a N(17 -140 -140 -0.5 0.5 'S -0.02 -80 0 -0.5 .I---QQ-... I 0 -1.0 -0.5 0.0 I- I -0.5 0.5 I -0.02 -80 0 -0.5 -140 -80 0.5 .: ................................... I 0.5 0 0.0 -80 _ _ -1.0 -0.5 I 0 Nf (cycles) 0.5 -0.02 0 VC(cycles) . I 0.02 -1.0 - -0.5 - - - - !- - - 0 - g 0. 0.5 V (cycles) Figure C-8: Post-TTX simultaneous-stimulimeasurement sets and model fits at 00 Hz on Cat #7. 185 Data set 200a-1 200b_l dB SPL 124 125;122 CMRR 8.46 8.55 ID 3.49e-07 3.48e-07 Linear model parameters: 200 Hz D IC ZC PMAG -0.113 1.32e-07 0.340 1.000 -0.114 1.30e-07 0.337 0.997 P/ 1.000 0.996 PMIN Data |MIN Model -0.0218 -0.0177 -0.0167 -0.0188 Table C.5: Linear model parameters calculated from 200 Hz data. Data set 200a_1 200b-1 dB SPL 124 125;122 Logarithmic model parameters: D C, /C 3.51e-07 -0.111 1.33e-07 0.341 3.41e-07 -0.115 1.28e-07 0.330 IDI CMRR 8.44 8.50 200 Hz PMAG 1.000 0.985 P/ 1.000 0.961 PMIN Data -0.0218 -0.0167 PMIN Model -0.0187 -0.0198 Table C.6: Logarithmic model parameters calculated from 200 Hz data. IVcpl (dB re 1 V) IVcpl -80 Qn -OU -100 -100 _ -120 _ (dB re 1 V) o Data points o Noisy data points Linear fit --- Logarithmicfit ZVcp (cycles) 1.0 --- -120 200a 1 noisefloor 124 dB SPL .oseo .. ............................. -140 . . . . ,i' -0.5 I I = 0 * ' 0.5 -140 I I ·. 0.5 0n_ -du r-' -0.05 t, . 0 . 0 0.05 -0.5 1.0 r -?u ,0. r_, -I . .. .... II 0 0.5 0 0.5 -100 _- 100 -120 0.5 -120 OW 125 dB SPL -140 RW 122 dB SPL . ..........I ............ . . . . .I . . -0.5 0 I1 I .. -140 I .... -! y (cycles) I_ I 0.5 -0.05 ......... ' I ' 0 0.05 f (cycles) 0 -0.5 V (cycles) Figure C-9: Simultaneous-stimuli measurement sets and model fits at 200 Hz on Cat #1. 186 Data set 250a_4 | r Linear model parameters: 250 Hz CMRR IDI | D Ic C I C I PMAG P/ I MIN Data PMIN Model 30.73 | 2.11e-06 -0.009 1 6.13e-08 1 0.396 1 0.998 | 0.925 1 -0.0092 1 -0.0027 dB SPL 108 Table C.7: Linear model parameters calculated from 250 Hz data. Data set 250a_4 Logarithmic model parameters: 250 Hz CMRR ID I LD IC I LC PMAG PI I MIN Data 39.60 1 2.23e-06 1 -0.005 1 2.33e-08 1 0.415 0.997 1 0.941 -0.0092 dB SPL 108 { PMI Model -0.0012 Table C.8: Logarithmic model parameters calculated from 250 Hz data. IVcpl (dB re 1 V) /Vcp (cycles) IVcpl (dB re 1 V) 1.0 -80 -80 -100 -100 -120 -120 o Data points * Noisy data points Linear fit --- Logarithmic fit 0.5 -140 , - noisefloor 'I v1 - -0.5 250a_4 108 dB SPL 0 ........................ 9 . - - - - - . - . - 0 ry (cycles) . - . - -140 I 0.5 . -0.01 . 0 I . · 0.01 I i (cycles) 0 -0.5 0 0.5 r (cycles) Figure C-10: Simultaneous-stimuli measurement set and model fits at 250 Hz on Cat #4. 187 Data set 300a.5 300b-5 300c_5 300d5 300e_5 300f.5 300a..6 300b..6 300c_6 300d_6 300e_6 300f_6 300g.6 300h_6 300i_6 300a_7 300b_7 300c_7 300d_7 300e_7 300f_7 300g_7 dB SPL 100 105 110 115 120 125 115 125 116 120 126 120 110 100 90 121 101 116 121 111 101 90 CMRR 24.36 26.18 34.40 33.89 33.51 37.08 33.11 28.53 31.24 35.58 34.83 39.62 42.89 49.11 31.42 31.78 39.41 47.32 36.65 35.27 18.60 32.38 IDI 6.20e-06 7.05e-06 6.82e-06 6.76e-06 6.41e-06 6.71e-06 1.20e-05 7.82e-06 1.05e-05 9.92e-06 7.35e-06 9.59e-06 9.50e-06 8.14e-06 7.82e-06 4.80e-06 4.21e-06 5.12e-06 5.74e-06 6.86e-06 4.94e-06 3.33e-06 Linear model parameters: 300 Hz ZD 7 Id LC PMAG -0.093 3.75e-07 -0.433 0.922 -0.132 3.46e-07 0.453 0.950 -0.165 1.30e-07 0.248 0.990 -0.181 1.37e-07 0.291 0.890 -0.153 1.35e-07 0.212 0.936 -0.175 9.39e-08 0.303 0.959 -0.236 2.66e-07 0.270 0.980 -0.258 2.93e-07 0.177 0.979 -0.217 2.87e-07 0.336 0.988 -0.231 1.65e-07 0.228 0.976 -0.237 1.33e-07 0.242 0.988 -0.224 1.00e-07 0.174 0.993 -0.202 6.81e-08 0.272 0.989 -0.209 2.85e-08 -0.029 0.984 -0.228 2.10e-07 0.228 0.981 7 0.408 0.976 -0.221 1.24e-0 -0.159 4.51e-08 -0.492 0.995 -0.214 2.20e-08 0.403 0.985 -0.252 8.44e-08 -0.461 0.993 7 -0.228 1.18e-0 -0.431 0.992 -0.179 5.80e-07 -0.500 0.902 -0.147 8.01e-08 0.421 0.995 P/ 0.769 0.564 0.499 0.512 0.847 0.865 0.982 0.960 0.964 0.882 0.970 0.994 0.962 0.879 0.969 0.960 0.990 0.874 0.989 0.993 0.571 0.984 'MIN Data 0.0104 0.0000 -0.0018 -0.0040 -0.0047 -0.0024 0.0014 -0.0003 -0.0007 -0.0016 -0.0012 -0.0011 -0.0006 -0.0001 0.0018 0.0015 0.0018 0.0011 0.0029 0.0026 0.0046 0.0034 'PMIN Model 0.0078 0.0036 -0.0011 -0.0011 -0.0029 -0.0002 0.0003 -0.0021 0.0007 -0.0011 -0.0007 -0.0011 -0.0005 -0.0008 -0.0009 0.0025 0.0015 0.0002 0.0020 0.0021 0.0170 0.0020 Table C.9: Linear model parameters calculated from 300 Hz data. Data set 300a..5 300b.5 300c_5 300d.5 300e_5 300f_5 300a_6 300b..6 300c_6 300d_6 300e_6 300f_6 300g_6 300h_6 300i-6 300a_7 300b_7 300c_7 300d_7 300e_7 300f_7 300g_7 dB SPL 100 105 110 115 120 125 115 125 116 120 126 120 110 100 90 121 101 116 121 111 101 90 CMRR 25.18 31.12 32.77 29.75 30.88 32.29 32.91 32.21 31.10 35.73 39.64 39.23 43.87 41.11 29.10 38.06 39.73 38.87 34.78 33.90 22.04 29.19 IDI 6.35e-06 7.96e-06 6.68e-06 5.07e-06 5.33e-06 5.55e-06 9.04e-06 9.41e-06 8.46e-06 8.00e-06 7.86e-06 8.49e-06 6.08e-06 7.51e-06 7.88e-06 3.71e-06 3.66e-06 4.44e-06 5.49e-06 5.69e-06 5.86e-06 3.10e-06 Logarithmic model parameters: 300 Hz D IcI C | PMAG | -0.082 3.50e-07 -0.488 0.961 0.785 -0.108 2.21e-07 0.458 0.946 0.656 -0.134 1.54e-07 0.156 0.919 0.722 -0.137 1.65e-07 0.082 0.985 0.817 -0.073 1.52e-07 0.253 0.993 0.938 -0.115 1.35e-07 0.315 0.990 0.942 -0.263 2.04e-07 0.263 0.992 0.972 -0.242 2.31e-07 0.257 0.991 0.994 -0.283 2.36e-07 0.264 0.995 0.920 -0.227 1.31e-07 0.161 0.998 0.994 -0.219 8.19e-08 0.173 0.998 0.997 -0.215 9.28e-08 0.140 0.997 0.997 -0.160 3.89e-08 0.133 0.986 0.924 -0.220 6.61e-08 0.011 0.981 0.873 -0.257 2.76e-07 0.229 0.997 0.986 -0.153 4.64e-08 0.315 0.980 0.917 -0.141 3.78e-08 0.457 0.996 0.989 -0.183 5.06e-08 0.486 0.995 0.976 -0.225 1.00e-07 -0.465 0.998 0.994 -0.206 1.15e-07 -0.397 0.995 0.995 -0.197 4.64e-07 -0.496 0.923 0.715 -0.160 1.08e-07 0.240 0.987 0.960 PMIN Data | MIN Model 0.0104 0.0048 0.0000 0.0010 -0.0018 -0.0038 -0.0040 -0.0052 -0.0047 -0.0042 -0.0024 -0.0009 0.0014 0.0000 -0.0003 -0.0003 -0.0007 0.0007 -0.0016 -0.0021 -0.0012 -0.0012 -0.0011 -0.0011 -0.0006 -0.0005 -0.0001 -0.0010 0.0018 -0.0005 0.0015 -0.0004 0.0018 0.0007 0.0011 0.0011 0.0029 0.0025 0.0026 0.0031 0.0046 0.0119 0.0034 -0.0033 Table C.10: Logarithmic model parameters calculated from 300 Hz data. 188 -OD -60 _ -80 ZVcp (cycles) IVcpl (dB re 1 V) 1Vcpl (dB re 1 V) _~f o Data points o Noisy data points Linear fit -80 1.0 --- Logarithmic fit -100 -100 -noisefloor -120 100 dB SPL ._.... r... ..... _ 0.5 -120 0 -140 -140 ga T . . -, -0.5 _ I I· Ia I 0.5 0 * -0.01 n, -Dv -Dv r" -80 -80 - I 0 0.01 -100 I I ._ -0.5 0 0.5 0a - 0.5 -120 I -1 A4 *7VI 0 1.0 I- -100 -120 I I -140 l l l I l l l I 0 0.5 0 -0.5 l Ii -0.01 -60 -60 -80 -80 -100 -100 -120 _ | 300c_5 -120 .................. ....i -140 110 dB SPL -140 ...... 11 . . . . -II ...--. . . . II 0 0.5 -0.5 n n n I yi (cycles) I I 0 0.01 0 -0.5 I 0 0.5 0 0.5 1.0 0.5 I -0.01 I I 0 0.01 lr (cycles) 0 -0.5 yv (cycles) Figure C-11: Simultaneous-stimuli measurement sets and model fits at 300 Hz on Cat #5. 189 IVcpl (dB re 1 V) crn -OU _ -ouv -80I -80 -100 I -100 -120 -140 300d_5 115 dB SPL ....................... noisefloor ...................... 1 1 1 1 1 I . -0.5 . . 0 I.U - I o Data points Linear fit --- Logarithmic fit _ 0.5 -120 I . ____ I . I . ,i . . 0.5 -0.01 -60 -oU -80 -80 I- n_ 0 300e_5 120 dB SPL r 0- 0.01 - I - - ... - i ! i i - -0.5 0 0,!5 -0.5 0 0.! 1.0 r"- -100 -120 I - -140 . -100 ZV c p (cycles) IVcpI (dB re 1 V) 0.5 -120 ·············· """""""··'······ -140 -140 . · .I -0.5 0 0.5 -0.01 -60 -ou -80 -80 -100 -100 300f_5 -120 125 dB SPL ................................................. -120 -140 -140 I I . I Ii 0 0 0.01 _, 1.0 _ 0.5 d I . . . 0 . . . . . . . . . . -0.5 0 0.5 ! -0.5 0 Mf(cycles) 0.5 -0.01 0 0.01 l (cycles) I Ni (cycles) Figure C-12: Simultaneous-stimuli measurement sets and model fits at 300 Hz on Cat #5. 190 -IOU -60 -80 -80 -100 -100 -120 -120 -140 300a_6 115 dB SPL - -0.5 -60 2 l l o Data points ! Il l 0 | l l ! l I 0.5 --- Logarithmic fit I ........ . ....... I I ! I -0.01 -80 -80 -100 -100 -120 -120 -140 -140 I ' 0 0.01 Mf(cycles) 0.5 -0.5 0 0.5 - 0.5 - - ! 0 0 1.0 - II -0.5 0.5 44~~ __ ,, -OU 1.0 - Linear fin -140 noisefloor .- LVcp (cycles) IVcpI (dB re 1V) lVcpl (dB re 1V) ,, 1................................... : ' -0.01 ., 0 0 . . . . . . . . . . :! I 0.01 v (cycles) -0.5 . . . 0 . I 0.5 iv(cycles) Figure C-13: Pre-TTX simultaneous-stimuli measurement sets and model fits at 300 Hz on Cat #6. 191 IVcpl (dB re 1V) IVcpl (dB re 1V) -60 111_ -fou r- 80 I K -80 -100 -100 -120 -120 _ 300i6 -140 - 90 dB SPL 9 noisefloor I.V o Data points Linear fit --- Logarithmicfit __ -140 A ·I I -0.01 0 -80 -80 _- -100 -100 _ -120 -120 -140 -140 0.5 -80 -100 1 1 1 i 1..................................... -140 -80 _- ................................................. ! 1·· · -0.5 0 · · I ' I 0 0.5 ._ _ 0. 5 0 II II 0. 5 I I II_ s 0.5 I 0 -0.01 0 _ -0.5 0.01 0 0.5 0 0.5 1.0 f,\ -Du r'- m- -0.5 1.0 .. _ 0 0 0.01 ..................................... I I ! : ;' i - - - - .. f Qo q - -140 1 -Ou -OU _, r- -120 . 0 -100 !3009_6 110 dBS PL I 0.5 -0.01 _ -120 -- - -0.5 1.0 I -60 U 0.01 r- -DU 0 I I 0.5 , ............ --9"k-v- -60 -0.5 F 0.5 'I1.... .... . .1 . , 1 ..................... .1. . 0 - _ I -0.5 ZVcp (cycles) -4 -80 _- -80 -100 -100 -120 - 3- 00c_6 116 dB SPL ~ -140 ~AA -1 0.5 ~~__ 3,_ -~_ U t_ -140 ................ I-0.5 -0.5 ........... I I 0 0.5 V (cycles) ................ ..................... i I I I, I -0.01 , I 0 0.01 v (cycles) 0 -0.5 i (cycles) Figure C-14: Post-TTX simultaneous-stimuli measurement sets and model fits at 300 Hz on Cat #6. 192 en _ -OV 1.0 u_ r -OU r'- _ -80 -80 -100 -100 -120 Zvcp (cycles) IVcpl (dB re 1V) lVcpl (dB re 1V) o Data points Linear fit --- Logarithmic fit - 0.5 -120 300d6 120 dB SPL -140 -140 - noisefloor I...................................... -0.5 0 . . . . a . . . . '..... ..... ..... *1 1 . I -0.01 0.5 A,, * 1 1 0 i...................... 0 1 a -ou -80 -80 _ ~,t' -100 -100 -120 -120 -140 -140 -0.5 0.01 1.0 -Ou I4ak 111 1 1~ - - -l - -l -l ..................................... -60 -0.01 ,-OUD -80 -80 _- 0 0.5 -100 -100 -120 -120 -140 -140 I I 0 0.01 0 v (cycles) 0.5 I -0.5 l l 00 0.5 0.5 0 0.5 1.0 1! 0.5 - I -0.5 0.5 0.5 I -0.5 0 _ -0.01 0 Ni(cycles) I . I I 0.01 0 -0.5 y (cycles) Figure C-15: Post-TTX simultaneous-stimuli measurement sets and model fits at 300 Hz on Cat #6. 193 IVcpl (dB re 1V) lVcpl (dB re 1V) 1-OUr1.0 -60 on -80 -80 -100 -100 -120 -120 -140 -140 o Data points Linear fit --- Logarithmicfit - 0.5 I I ,, -0.5 0 0.5 -tbU -80 -80 100 -100 120 -120 140 -140 0 0.5 -80 I 0.01 ! 0.0 0.01 -0.5 1.0 0 0.5 _ _ _ 0.5 0-00010 i i ..................................... 1 .' . * I 0 I I 0.0 !. I . -0.5 0.01 . . . . . . .I-.. . I . . . _ . . . * . * |. n . 0 0.5 0 0.5 1.0 7 -80 !- -100 -100 -120 -120 -140 0 -0.01 -60 . _, II -0.5 -60 I" 0I 0.01 -0.01 -OU ZVcp (cycles) _ 300a_7 121 dB SIPL ! -! -0.5 I I Q~4O -140 ................................................. : 0.5 -os l' 0 Nf (cycles) l I I i 0.5 -0.01 ll , 1 0 I 0.01 v (cycles) 0.0 -0.5 Nf (cycles) Figure C-16: Pre-TTX simultaneous-stimulimeasurement sets and model fits at 300 Hz on Cat #7. 194 IVcpI (dB re 1V) _ on I"' -OLv enr -Ou -80 _- -80 1.0 o Data points . Noisy data points Linear fit --- Logarithmicfit - 100 I -100 120 -120 I- 140 * 90 dBSPL noisefloor ........ a a . . -0.5 an -ouDv . ................... . . a 0.5 140 . -- 0 I · -0.01 0.5 -80 _ -100 -100 _ -120 -120 -140 -140 0 <b -80 -80 t- -100 -100 t111 dB SPIL ................................................. I - - -0.5 -OU - - - 0 - -Dv 0 0.5 I ·, 0.0 I I I 0 0.01 -0.5 I ~11B ~ ............................... .I' II ' I | 0 | * 0.01 0.0 . .. .. .. .. -0.5 eoolo. - - -. 0 0.5 1.0 m -80 _ -80 -100 -100 -120 -140 -0.01 _ w 1 0.5 ., 0.5 0.5 I ...... - 0 8 -140 I 1 - o 1.0 __ -120 · -0.5 0.01 .................................... I-- -120 0.0 0.5 -Do ore 0 I 1.0 I -0.01 0.5 _ .- · m -80 -140 I -oun _ _ -0.5 -60 ZVcp (cycles) IVcpl (dB re 1V) -120 121 300d_7 121 dB SPL .............................. 1 . . . ........... .. ... _ _ -0.5 vi . _ , I I_ 0 0.5 (cycles) -140 7v I I -0.01 0 r (cycles) 0.5 0.0 0.01 W000010 a: a -0.5 l l l 0 l l I 0.5 v (cycles) Figure C-17: Post-TTX simultaneous-stimuli measurement sets and model fits at 300 Hz on Cat #7. 195 Data set 400aJl 400b_1 400a_2 400a_3 400b.3 400c.3 400d_3 400e.3 400f_3 400g.3 dB SPL 110 110;108.5 114;113 112 113 115;114 113;114 113;114 114 114 IDI 1.25e-06 1.24e-06 9.42e-07 1.26e-06 1.13e-06 1.08e-06 1.07e-06 1.08e-06 1.Ole-06 9.88e-07 CMRR 13.21 13.49 19.37 23.15 28.79 34.58 19.07 23.74 40.09 33.24 Linear model parameters: 400 Hz D CI C PMAG -0.227 2.74e-07 0.342 0.999 -0.231 2.62e-07 0.342 0.999 -0.018 1.01e-07 -0.493 0.846 -0.189 8.79e-08 -0.472 0.983 -0.190 4.11e-08 -0.322 0.991 -0.195 2.01e-08 -0.338 0.993 -0.193 1.19e-07 -0.465 0.959 -0.188 7.00e-08 -0.403 0.970 -0.183 9.95e-09 -0.207 0.971 -0.183 2.15e-08 -0.213 0.992 P/ 1.000 0.989 0.807 0.966 0.964 0.997 0.915 0.917 0.973 0.976 MIN Data 0.0159 0.0155 -0.0034 0.0118 0.0042 0.0130 0.0156 0.0085 0.0029 0.0019 MIN Model 0.0150 0.0152 0.0025 0.0109 0.0042 0.0027 0.0175 0.0105 -0.0001 0.0009 Table C.11: Linear model parameters calculated from 400 Hz data. | Data set 400al 400bl 400a_2 400a_3 400b_3 400c_3 400d_3 400e.3 400f.3 400g.3 dB SPL 110 110;108.5 114;113 112 113 115;114 113;114 113;114 114 114 CMRR 13.23 13.40 25.50 23.51 32.46 32.03 18.61 23.58 35.54 34.08 IDI 1.28e-06 1.28e-06 1.28e-06 1.32e-06 1.15e-06 1.11e-06 1.lOe-06 1.lle-06 1.15e-06 1.lle-06 Logarithmic model parameters: 400 Hz D IC| C PMAG |P/ |MIN Data | MIN Model -0.227 2.79e-07 0.343 1.000 1.000 0.0159 0.0150 -0.228 2.73e-07 0.348 0.999 0.997 0.0155 0.0152 -0.019 6.77e-08 0.403 0.939 0.848 -0.0034 -0.0035 -0.174 8.80e-08 -0.444 0.990 0.974 0.0118 0.0109 -0.169 2.73e-08 -0.324 0.995 0.983 0.0042 0.0018 -0.176 2.78e-08 -0.448 0.995 0.999 0.0130 0.0042 7 -0.465 0.954 -0.194 1.29e-0 0.925 0.0156 0.0185 -0.164 7.35e-08 -0.403 0.993 0.976 0.0085 0.0105 -0.165 1.92e-08 -0.182 0.990 0.980 0.0029 0.0009 -0.166 2.20e-08 -0.174 0.995 0.985 0.0019 -0.0000 Table C.12: Logarithmic model parameters calculated from 400 Hz data. 196 '3 -OU -80 _ m . _ 1 .U 7 _ 400a_1 110 dB SPL - noisefloor .em emN... . -U--T - laf... . &$ . ......... e....E..E.E . -0.5 . . - . I 02 -1 20 -120 400b_1 OW110 dB SPL RW 108.5 dlB SPL_ 1 4 . ... . . . . . -- - -0.5 . . . , . . r 0 I _ I I -0.02 -80 -100 . . I I* 0.5 _- 0.5 -140 I 100 -140 i__111.-B- . . 0 -OUr- B o Data points - I Linear fit ... ___ . .! I..I I--- Logantnmic ='"1 -120 _ 140 A -100 100 120 LVcp (cycles) IVcpl (dB re 1V) IVcpI (dB re 1V) 0I 0 0.02 0 -0.5 1.0 I I 0 0.5 0 0.5 0.5 0 0 I . .- -0.02 0.5 0 0.02 -0.5 v (cycles) i (cycles) v (cycles) Figure C-18: Simultaneous-stimuli measurement sets and model fits at 400 Hz on Cat #1. iVcpl (dB re 1V) r- _ tn '- -OU -OU -100 vff~~~~~~.. -120 -120 -140 noisefloor - 1 -0.5 400a_2 OW 114 dS SPL RW 113 dB SPL * a 1 0 Mf (cycles) o Data points o Noisy data points Linear fit --- Logarithmic fit - o0 O- 0.5 -140 a1 I· 0.5 1.0 I - -100 ZVcp (cycles) lVcpl (dB re 1V) -0.02 ° 0 r (cycles) iI 0.02 0 -0.5 0 0.5 r (cycles) Figure C-19: Simultaneous-stimuli measurement set and model fits at 400 Hz on Cat #2. 197 IVcpl (dB re 1V) _, -100 -100 20 -120 112 dB SPL .................. 1 .. . -0.5 - 1.. 1I 0 0.5 I I -0.5 ,, U I -140 0 lI 7 -0.02 ,%n -bU r-- 100 -100 _- 120 -120 400b_3 113 dB SPL 140 0 0.02 , . . . . . . I . -0.5 . . . . 0 0.5 0 0.5 0 0.5 1.0 0.5 -140 - - - - - - - - - -0.5 0 0.5 l ! 1 l l r QN _ -Or 1 I 1 I -0.02 -ou 0 I I 0.02 on -100 0 -0.5 1.0 -100 p 400c_3 OW 115 dB SPL RW 114 dB SPL -120 -140 I........ 1 I . . . * . 1I . . . 1 . 0 1 I -100 ....·....... I I 0.5 0 .VIIU.4J 0.5 -120 -140 .................................... -0.5 -80 ·...................... · I 0 -0.02 -80 · I 0.02 OW 113 dEI SPL RW114dE 3SPL .................... -140 I ................... L . -0.5 .1 1. .1 1. 1. .1 1 1 1 ! I 0 0.5 N (cycles) -0.5 0 0.5 -120 400d3 0 1.0 -100 -120 -140 J 0.5 400a_3 noisefloor ................... -140 1.0 -80 -?U r-- -1 ZVcp (cycles) IVcpl (dB re 1V) _ . . . .I . . . . -0.02 0 Mf (cycles) 0.02 -0.5 I I 0 0.5 ! v (cycles) Figure C-20: Simultaneous-stimuli measurement sets and model fits at 400 Hz on Cat #3. 198 -80 on -au -100 -100 -120 0.5 tOW113dBSPL - RW114dBSPL 1 1 1 1 1 -0.5 -ou 1.0 -120 400e_3 nosiefloor -140 -140 0 1 1 1 1 1 0.5 0 -0.02 0 0.C)2 -80 -100 -100 -120 -120 -140 -140 0.5 0 -80o 0.5 0 -0.5 I.U 0.5 1 -0.5 ZVcp (cycles) IVcpl (dB re 1V) lVcpl (dB re 1V) -0.02 -80 - II8 8 0 IJ I 0.02 0I - I .... . -0.5 . . 1 0.5 0 1.0 I -100 -100 -120- -120 q -140 " i 14 uOr OrL .......................................... .... -0.5 -140 Il.... , I 0 0.5 yr (cycles) 0.5 .................................. -0.02 0 N (cycles) 0ea"" 0I : I 0.02 -0.5 i 0 0.5 A (cycles) Figure C-21: Simultaneous-stimuli measurement sets and model fits at 400 Hz on Cat #3. 199 Linear model parameters: 500 Hz I Data set dB SPL CMRR I DI I D I CI I C I PMAG I I MIN Data 500a4 1 97 1 28.82 4.45e-06 1 -0.230 1.61e-07 0.353 0.992 0.958 0.0026 MIN Model 0.0025 Table C.13: Linear model parameters calculated 500 Hz data. Logarithmic model parameters: 500 Hz Data set dB SPL 500a_4 | 97 I i ICI I I MIN Data IMIN Model C I PMAG I P/ 1.49e-07 1 0.324 1 0.994 | 0.968 0.0026 1 0.0000 CMRR ID] I D 29.00 | 4.19e-06 1 -0.187 Table C.14: Logarithmic model parameters calculated from 500 Hz data. (dB re 1 V) IVcpl ZVcp (cycles) IVcpl (dB re 1 V) 1.0 -80 o Data points -80 -100 -100 -120 -120 -- Linearfit --- Logarithmic fit 0.5 -140 -m X 500a_4 -_ noisefloor B 97 dBSPL ................................................. Ii -0.5 :: . . I I 0 xN(cycles) : : 'I -140 0 0 - D ..................................... 0 ! 0.5 ! -0.01 0 x (cycles) 0.01 -0.5 0 r (cycles) 0.5 Figure C-22: Simultaneous-stimuli measurement set and model fits at 500 Hz on Cat #4. 200 Data set 600a..1 600b..1 600c 1 dB SPL 106;105 113;112 100 CMRR 15.37 15.22 14.72 jDI 2.60e-06 2.40e-06 2.67e-06 Linear model parameters: 600 Hz CI [ C PMAG D -0.331 4.43e-07 0.336 0.998 -0.344 4.16e-07 0.328 0.995 -0.330 4.91e-07 0.340 0.997 P 1.000 0.998 0.973 gIN Data 0.0196 0.0246 0.0224 MIN Model 0.0237 0.0245 0.0245 Table C.15: Linear model parameters calculated from 600 Hz data. Data set 600a 1 600bl1 600c dB SPL 106;105 113;112 100 CMRR 15.20 15.27 15.11 Logarithmic model parameters: C /D ICI 2.74e-06 -0.329 4.77e-07 0.340 2.83e-06 -0.348 4.87e-07 0.325 2.70e-06 -0.324 4.74e-07 0.339 IDI 600 Hz PMAG 0.999 0.999 0.999 P I MIN Data 1.000 0.0196 0.998 0.0246 0.988 0.0224 PMIN Model 0.0237 0.0245 0.0239 Table C.16: Logarithmic model parameters calculated from 600 Hz data. 201 -ou .1 - QN _ -aU m 0.5 _J 100 -100 20 -120 -1 zVcp (cycles) lVcpI (dB re V) IVcpl (dB re 1V) o Datapoints Linear fit -- Logarithmic fit 0 600c 1 140 noisefloor - 100dBSPL -140 ................................................. I r . · -0.5 Q" -OU · I r · 0 0.5 _ w -0.05 -80 100 -100 120 -120 140 600a OW 106 dE3 SPL RW .......... 105dE3SPL . - 'I 1 1- I1 .1 . -0.5 Ore -Ot I .. . ..................... I I 0 0.5 m 20 -140 0 0.05 -0.5 -0.5 0.5 0 0.5 _ 0 -140 -0.5 I -0.05 -80 0 0.05 'l l l' l l' -0.5 0.5 l' ! l l l 0 l l ! 0.5 -100 -100 -1 ..................................... ·I ,'· , , · 1 · 0 -120 - 3 SPL SPI - .... -140 I ........................... Ad· · -0.5 · * ·. .* . I · x' . r . 0 ir (cycles) -0.5 I I 0.5 -0.05 0 fr (cycles) 0.05 · -0.5 l - . l l.l.l I 0 l I 0.5 Vr (cycles) Figure C-23: Simultaneous-stimuli measurement sets and model fits at 600 Hz on Cat #1. 202 Data set 800al1 800b1 800a.3 800a_4 800b_4 dB SPL 116 116 116 103 98 CMRR 16.55 16.31 19.82 31.56 37.12 IDI 3.25e-06 3.19e-06 2.34e-06 7.35e-06 6.76e-06 Linear model parameters: 800 Hz /_C PMAG LD I 0.999 -0.437 4.84e-07 0.260 0.998 -0.434 4.88e-07 0.271 0.968 -0.354 2.39e-07 0.387 0.995 -0.335 1.94e-07 0.446 -0.324 9.42e-08 -0.299 0.992 P 1.000 0.999 0.947 0.991 0.985 O3MIN Data 0.0228 0.0233 0.0164 0.0041 0.0006 'MIN Model 0.0227 0.0232 0.0159 0.0041 0.0001 Table C.17: Linear model parameters calculated from 800 Hz data. Data set 800a1 800b 800a.3 800a_4 800b_4 dB SPL 116 116 116 103 98 CMRR 16.54 16.32 19.58 31.74 33.94 IDI 3.40e-06 3.41e-06 3.19e-06 7.40e-06 5.87e-06 Logarithmic model parameters: 800 Hz /CPMAG D ICI' 1.000 -0.436 5.06e-07 0.261 0.999 -0.432 5.20e-07 0.272 0.989 -0.348 3.35e-07 0.426 0.996 -0.330 1.91e-07 0.477 -0.342 1.18e-07 -0.324 0.991 Data P IMIN 1.000 0.0228 0.999 0.0233 0.988 0.0164 0.993 0.0041 0.992 0.0006 'PMIN Model 0.0227 0.0232 0.0169 0.0041 0.0001 Table C.18: Logarithmic model parameters calculated from 800 Hz data. IVcpl (dB re 1 V) IVcpI (dB re 1 V) ZVcp (cycles) 0.5 -80 _ o Data points Linear fit --- Logarithmic fit -80 _ -100 -100 -120 -120 .- O 104 dB SPL noisefloor ...................................... -140 1 1..1 . . . . . . 1 0 0.5 -0.5 0 -140 0 . 5 . ... I ..... ... . . 0 . . -0.02 . . 0.02 -0.5 -0.5 0 0.5 0 0.5 0.5 -80 _ -80 -100 -100 0 -120 ~800b_ 104 -140 I. -0.5 . -120 A..........L W _ . . . ! .. . . 0 . - V (cycles) dB SPL I . 0.5 -140 I I 1 I -0 .02 0 0.02 xV(cycles) -0.5 -0.5 V (cycles) Figure C-24: Simultaneous-stimuli measurement sets and model fits at 800 Hz on Cat #1. 203 IVcpl (dB re 1 V) IVcpl (dB re 1 V) ZVcp (cycles) 0.5 -80 -80 -100 -100 o Datapoints -Linear fit --- Logarithmic fit 0 -120 800a_3 116 dB SPL noisefloor -140 '11 I . .. .. . 11 0.5 E -140 1 1 1 A1 0 -0.5 -120 ................... 1 I 1 -0.02 1 I 1 0 1··············I I -0.5 I 0.02 . " .... ' -0.5 . "'. I * ' . . I .1 0 0.5 v (cycles) v (cycles) v (cycles) ' Figure C-25: Simultaneous-stimuli measurement set and model fits at 800 Hz on Cat #3. lVcpl (dB re 1 V) ZVcp (cycles) IVcpI (dB re 1 V) AI U.U -80 -80 -100 -100 -120 -120 o Data points - Linear fit K --- Logarithmicfit 0 -140 800b_4 noisefloor 98 dB SPL .................. ........................ 1 -0.5 *-. e. -140 . . . . I . . .B , 0.5 / .................................. 1 0 .- -0.02 0 I -0.5 . . ! . I I .5 0.02 -0.5 0 0.5 0 0.5 0.5 -80 -80 I-100 -100 I- 0 -120 -120 -140 -140 -0.5 0 Vi (cycles) 0.5 . ........ . ............. ' I -0.02 0 Ay (cycles) · I 0.02 -0.5 -0.5 i (cycles) Figure C-26: Simultaneous-stimuli measurement sets and model fits at 800 Hz on Cat #4. 204 I - Data set dB SPL 1000la1 101 10OObl 100 1000OOa 101;99 10O0b.2 110;108 10OOc2 111;108 1000a-3 110 1000b3 110 1000c-3 111 1000d-3 111 10OOe.3 111 1OOOf_3 111 0l0g.3 112 1000h3 111 100Oi3 111 1000j-3 112 10OOk-3 112 100013 109;113 10OOm_3 113 1000n3 102 lOOO_4 106 lOOOb_4 98 10cOO_4 106 1OOOd_4 106 1000e_4 106 1000f_4 98 lOOOg_4 106 1000a.5 103 10OOb5 102.5;102.5 100lOOOc5103.2;101.9 1OOOd..5 103.7;101.2 10OOe_5 104.4;100.5 10OOf.5 103.0;102.3 1OOOg5 105 lOOOh..5 110 1000i5 115 1000j..5 100 10OOk.5 95 100015 110 10OOm5 105 O1OOn_5 100 10OOp.5 95 1000lq5 90 1000r..5 115 1000l 5 120 l000a6 104 10OOb_6 114 10OOc..6 104 10OOd-6 113 1000e_6 98 1000f_6 98 10OOg_6 110 10OOh_6 100 1000i_6 90 1000j_6 80 10OOk_6 120 10OOa_7 119 10OOb_7 99 1000c_7 109 10OOd-7 99 1000e_7 89 1000f_7 119 CMRR 17.85 17.77 13.36 12.33 12.43 16.30 16.42 20.15 20.49 18.61 16.88 21.81 15.68 46.08 23.64 17.37 12.21 15.23 14.88 31.23 32.97 33.64 28.80 44.01 44.63 44.95 25.45 31.81 24.68 29.62 29.43 27.07 26.83 25.94 25.21 29.02 33.94 25.65 25.77 23.30 29.04 21.86 26.70 22.65 36.78 34.17 28.06 30.97 37.10 33.82 32.45 32.33 33.81 21.43 29.09 31.96 33.25 34.67 35.04 35.15 37.49 -Di 2.84e-06 2.90e-06 5.63e-06 5.71e-06 5.58e-06 4.51le-06 4.43e-06 4.13e-06 4.1le-06 4.06e-06 3.90e-06 3.73e-06 3.94e-06 3.89e-06 3.78e-06 3.83e-06 3.35e-06 3.14e-06 3.64e-06 7.96e-06 8.29e-06 7.36e-06 7.43e-06 7.18e-06 7.42e-06 6.99e-06 1.71e-05 1..77e-05 1.78e-05 1.76e-05 1.77e-05 1.77e-05 1.76e-05 1.68e-05 1.71e-05 1.70e-05 1.63e-05 1.17e-05 1.22e-05 1.21e-05 1.24e-05 1.22e-05 9.34e-06 6.65e-06 1.70e-05 1.63e-05 1.45e-05 1.46e-05 1.39e-05 1.36e-05 1.43e-05 1.39e-05 1.40e-05 1.40e-05 1.22e-05 1.06e-05 1.31e-05 5.65e-06 5.64e-06 5.81e-06 4.24e-06 Linear model parameters: 1000 Hz ZD Ic, LC PMAG -0.499 3.64e-07 0.264 0.999 0.499 3.75e-07 0.272 0.998 -0.383 1.21e-06 0.226 0.974 -0.396 1.38e-06 0.184 0.986 -0.395 1.33e-06 0.184 0.971 -0.394 6.90e-07 0.488 0.986 -0.395 6.70e-07 0.492 0.983 -0.385 4.06e-07 0.478 0.993 -0.387 3.88e-07 0.493 0.950 -0.388 4.76e-07 0.316 0.990 -0.393 5.59e-07 0.291 0.995 -0.390 3.03e-07 0.259 0.987 -0.372 6.48e-07 -0.157 0.980 -0.383 1.93e-08 0.032 0.989 -0.390 2.48e-07 0.289 0.965 -0.397 5.18e-07 0.281 0.998 -0.404 8.22e-07 0.272 0.996 -0.406 5.44e-07 0.281 0.986 -0.388 6.56e-07 0.308 0.986 -0.421 2.19e-07 0.244 1.000 -0.406 1.86e-07 0.303 0.998 -0.426 1.53e-07 0.066 1.000 -0.421 2.70e-07 0.096 0.999 -0.421 4.53e-08 0.345 0.999 -0.407 4.35e-08 0.400 0.998 -0.419 3.95e-08 0.196 0.999 -0.435 9.11e-07 0.394 0.974 -0.427 4.53e-07 0.450 0.965 -0.426 1.04e-06 0.347 0.989 -0.424 5.80e-07 0.376 0.997 -0.425 5.96e-07 0.398 0.999 -0.425 7.83e-07 0.366 0.988 -0.428 8.00e-07 0.474 0.928 -0.431 8.47e-07 0.430 0.982 -0.425 9.37e-07 0.433 0.961 -0.433 6.00e-07 0.298 0.878 -0.452 3.27e-07 0.335 0.728 -0.510 6.11e-07 -0.294 0.939 -0.504 6.26e-07 -0.283 0.985 -0.502 8.31e-07 -0.237 0.958 -0.515 4.38e-07 -0.306 0.953 -0.535 9.86e-07 -0.205 0.925 .0.513 4.32e-07 -0.352 0.991 -0.513 4.90e-07 -0.453 0.969 -0.475 2.47e-07 0.227 0.960 -0.485 3.19e-07 -0.260 0.968 -0.466 5.72e-07 -0.317 0.999 -0.483 4.12e-07 0.007 0.991 -0.451 1.94e-07 0.044 1.000 -0.456 2.76e-07 -0.144 0.999 -0.477 3.40e-07 -0.157 1.000 -0.458 3.36e-07 -0.267 0.969 -0.449 2.85e-07 -0.175 0.999 -0.449 1.19e-06 -0.003 0.997 -0.497 4.30e-07 -0.255 0.985 -0.459 2.67e-07 0.129 0.979 -0.433 2.86e-07 0.318 0.979 -0.431 1.04e-07 0.147 0.996 -0.393 9.98e-08 0.220 0.997 -0.370 1.02e-07 0.096 1.000 -0.452 5.66e-08 0.063 0.972 P 1.000 0.999 0.911 0.988 0.988 0.994 0.983 0.976 0.932 0.939 0.941 0.978 0.942 0.987 0.940 0.965 0.996 0.986 0.981 0.996 0.997 0.998 0.996 0.992 0.993 0.994 0.832 0.842 0.992 0.999 1.000 0.974 0.874 0.961 0.964 0.385 0.602 0.781 0.628 0.751 0.778 0.635 0.996 0.995 0.837 0.859 0.999 0.986 0.999 0.999 0.601 0.935 0.993 0.999 0.991 0.923 0.896 0.973 0.989 0.998 0.850 OMIN Data 0.0201 0.0203 0.0018 0.0260 0.0260 0.0152 0.0139 0.0096 0.0093 0.0185 0.0210 0.0127 -0.0278 -0.0016 0.0078 0.0198 0.0283 0.0231 0.0335 0.0022 0.0029 0.0002 -0.0013 0.0023 -0.0010 -0.0001 0.0104 0.0104 0.0030 -0.0050 0.0025 0.0043 0.0067 0.0018 0.0045 0.0108 0.0137 -0.0083 -0.0099 -0.0092 0.0006 0.0067 -0.0085 -0.0028 0.0068 -0.0025 -0.0024 -0.0015 -0.0010 -0.0034 -0.0041 -0.0037 -0.0039 -0.0236 -0.0049 0.0034 0.0020 0.0005 0.0001 0.0007 0.0004 Table C.19: Linear model parameters calculated from 1000 Hz data. 205 MIN Model 0.0204 0.0204 0.0217 0.0187 0.0178 0.0162 0.0159 0.0120 0.0094 0.0170 0.0210 0.0098 -0.0258 -0.0006 0.0098 0.0193 0.0353 0.0252 0.0272 0.0036 0.0029 -0.0007 -0.0015 0.0013 0.0010 0.0009 0.0071 0.0015 0.0089 0.0050 0.0049 0.0067 0.0017 0.0066 0.0063 0.0060 0.0033 -0.0083 -0.0089 -0.0112 -0.0056 -0.0113 -0.0087 -0.0031 0.0022 -0.0035 -0.0077 -0.0005 -0.0015 -0.0034 -0.0036 -0.0040 -0.0033 -0.0041 -0.0058 0.0024 0.0030 0.0018 0.0011 -0.0007 0.0001 Data set dB SPL 1000al. 101 10Ob1 100 1000a..2 101;99 1000b..2 110;108 1000c_2 111;108 1000la_3 110 1000b3 110 1000c_3 111 1000d.3 111 00OOe..3 111 00OOff3 111 1000g_3 112 1000h.3 111 1000i.3 111 1000j_3 112 1000k.3 112 10001_3 109;113 1000m-3 113 1000n.3 102 1000a_4 106 1000b_4 98 1000c4 106 1000d_4 106 1000e_4 106 1000f_4 98 1000g_4 106 1000a_5 103 1000b5 102.5;102.5 1OOOc5 103.2;101.9 1000d_5 103.7;101.2 1000e.5 104.4;100.5 1000f_5 103.0;102.3 1000g_5 105 10OOh.5 110 10005 115 1000j_5 100 1000k_5 95 10001_5 110 1OOOm_5 105 10OOn5 100 10OOpS 95 lO000q5 90 10OOr-5 115 1OOO5 120 1000a_6 104 10OOb_6 114 10OOc_6 104 100OOd6 113 10OOe_6 98 10OOf.6 98 lO1000g6 110 10OOh_6 100 1000i-6 90 1000j_6 80 10OOk_6 120 1000laJ 119 10OOb_7 99 10OOc_7 109 10OOd_7 99 10OOe_7 89 1000f_7 119 CMRR 18.02 18.16 16.77 13.01 13.16 16.53 16.27 20.62 20.47 18.32 17.19 21.15 15.46 43.54 23.45 17.13 12.66 15.25 14.07 32.12 33.29 33.45 28.99 44.22 45.13 47.31 26.09 33.55 26.21 27.42 30.56 22.88 27.53 26.59 24.69 23.68 21.44 25.51 23.41 22.14 39.82 16.83 27.58 24.92 30.34 38.00 28.91 34.35 36.94 33.56 32.48 32.74 33.40 20.69 30.11 32.10 30.77 35.50 37.79 35.29 43.93 Logarithmic model parameters: 1000 Hz IDI D ICI C PMAG 2.98e,06 -0.499 3.74e-07 0.263 1.000 3.06e-06 0.499 3.79e-07 0.271 0.999 4.54e-06 -0.381 6.58e-07 0.155 0.968 5.48e-06 -0.381 1.23e-06 0.207 0.996 5.15e-06 -0.382 1.13e-06 0.209 0.992 5.20e-06 -0.385 7.75e-07 -0.488 0.997 5.04e-06 -0.390 7.73e-07 -0.489 0.998 4.70e-06 -0.380 4.38e-07 -0.497 0.998 4.49e-06 -0.378 4.25e-07 -0.485 0.998 4.64e-06 -0.377 5.63e-07 0.350 0.997 4.37e-06 -0.379 6.04e-07 0.312 0.997 4.10e-06 -0.378 3.59e-07 0.275 0.995 4.25e-06 -0.353 7.16e-07 -0.128 0.997 4.42e-06 -0.364 2.94e-08 0.125 0.995 4.12e-06 -0.360 2.77e-07 0.295 0.997 4.07e-06 -0.379 5.66e-07 0.302 0.998 3.45e-06 -0.400 8.03e-07 0.280 0.997 3.56e-06 -0.382 6.16e-07 0.298 0.997 3.65e-06 -0.373 7.22e-07 0.312 0.996 8.11e-06 -0.416 2.01e-07 0.241 1.000 8.48e-06 -0.407 1.84e-07 0.280 0.999 7.55e-06 -0.418 1.61e-07 0.060 1.000 7.49e-06 -0.412 2.66e-07 0.105 0.999 7.10e-06 -0.408 4.37e-08 0.319 1.000 7.21e-06 -0.400 3.99e-08 0.432 0.999 6.90e-06 -0.406 2.97e-08 0.188 1.000 1.54e-05 0.462 7.65e-07 0.208 0.991 1.48e-05 0.479 3.10e-07 0.478 0.958 1.75e-05 -0.474 8.57e-07 0.274 0.994 1.76e-05 -0.431 7.47e-07 0.335 0.996 1.78e-05 -0.427 5.27e-07 0.366 0.999 1.72e-05 -0.461 1.23e-06 0.273 0.978 1.36e-05 0.495 5.73e-07 0.267 0.982 1.67e-05 -0.479 7.82e-07 0.364 0.986 1.67e-05 -0.458 9.71e-07 0.399 0.948 1.46e-05 0.400 9.55e-07 0.100 0.984 1.40e-05 0.348 1.19e-06 -0.476 0.584 1.38e-05 0.455 7.34e-07 -0.290 0.995 1.37e-05 0.433 9.26e-07 -0.279 0.995 1.42e-05 0.427 1.lle-06 -0.284 0.993 1.44e-05 0.368 1.47e-07 0.469 0.949 1.07e-05 0.428 1.54e-06 -0.229 0.942 1.08e-05 0.479 4.53e-07 -0.345 0.995 8.60e-06 0.490 4.88e-07 -0.407 0.982 1.25e-05 -0.491 3.82e-07 0.192 0.983 1.26e-05 -0.472 1.59e-07 -0.184 0.981 1.44e-05 -0.451 5.16e-07 -0.292 1.000 1.44e-05 -0.463 2.75e-07 -0.016 1.000 1.35e-05 -0.447 1.91e-07 0.043 1.000 1.31e-05 -0.452 2.75e-07 -0.137 1.000 1.14e-05 -0.375 2.72e-07 -0.166 0.993 1.55e-05 -0.464 3.58e-07 -0.308 0.999 1.37e-05 -0.451 2.93e-07 -0.182 0.999 1.34e-05 -0.452 1.24e-06 -0.021 0.998 1.32e-05 -0.464 4.13e-07 -0.250 1.000 1.19e-05 -0.451 2.96e-07 0.211 0.999 9.48e-06 -0.431 2.74e-07 0.278 0.981 5.77e-06 -0.399 9.68e-08 0.128 1.000 5.68e-06 -0.374 7.33e-08 0.187 1.000 5.77e-06 -0.367 9.94e-08 0.090 1.000 5.13e-06 -0.406 3.27e-08 0.378 0.998 P 1.000 1.000 0.889 0.997 0.997 0.999 0.996 0.999 0.999 0.998 0.995 0.989 0.988 0.994 0.977 0.980 0.997 0.993 0.991 0.998 0.998 0.999 0.999 0.996 0.994 0.996 0.943 0.673 0.992 1.000 1.000 0.995 0.959 0.982 0.990 0.702 0.530 0.979 0.957 0.921 0.851 0.876 0.997 0.999 0.925 0.946 0.999 0.995 0.999 1.000 0.985 0.999 0.996 1.000 0.999 0.994 0.976 0.985 0.997 0.998 0.979 MIN Data 0.0201 0.0203 0.0018 0.0260 0.0260 0.0152 0.0139 0.0096 0.0093 0.0185 0.0210 0.0127 -0.0278 -0.0016 0.0078 0.0198 0.0283 0.0231 0.0335 0.0022 0.0029 0.0002 -0.0013 0.0023 -0.0010 -0.0001 0.0104 0.0104 0.0030 -0.0050 0.0025 0.0043 0.0067 0.0018 0.0045 0.0108 0.0137 -0.0083 -0.0099 -0.0092 0.0006 0.0067 -0.0085 -0.0028 0.0068 -0.0025 -0.0024 -0.0015 -0.0010 -0.0034 -0.0041 -0.0037 -0.0039 -0.0236 -0.0049 0.0034 0.0020 0.0005 0.0001 0.0007 0.0004 PMIN Model 0.0194 0.0192 0.0046 0.0187 0.0188 0.0143 0.0138 0.0096 0.0089 0.0187 0.0210 0.0117 -0.0268 -0.0006 0.0088 0.0203 0.0333 0.0252 0.0292 0.0036 0.0029 -0.0007 -0.0015 0.0013 0.0007 0.0001 0.0084 -0.0004 0.0076 0.0065 0.0049 0.0118 0.0066 0.0066 0.0063 0.0098 -0.0123 -0.0081 -0.0109 -0.0120 -0.0012 -0.0196 -0.0046 -0.0031 0.0042 -0.0020 -0.0028 -0.0012 -0.0015 -0.0034 -0.0041 -0.0032 -0.0033 -0.0061 -0.0051 0.0033 0.0040 0.0002 0.0010 -0.0007 0.0001 Table C.20: Logarithmic model parameters calculated from 1000 Hz data. 206 ZVcp (cycles) IVcpl (dB re 1V) IVcpl (dB re 1V) 0.5 -80 _- -80 - -100 o Data points o Noisy data points -100 - Linearfit --- Logarithmic fit 0 -120 -140 no1000b 1L ..--------------noisefloor |100 dB SPL ............. I - -. -0.5 - - - I - - - 0 - -120 -140 a lI 0.5 -0.02 · II · 0 II -0.5 -0.5 0.02 0 0.5 0.5 -80 -80 -100 -100 -120 -120 -140 -140 m - O i f' I. i -0.5 0 v (cycles) 0.5 -0.02 -0.5 . I 0 0.02 'v(cycles) -- -- -- -- -- A I I -0.5 0 - - - I 0.5 v (cycles) Figure C-27: Simultaneous-stimuli measurement sets and model fits at 1000 Hz on Cat #1. 207 ZVCP (cycles) IVcpl (dB re 1V) lVcpl (dB re 1V) _ U.O r-- -80 _ o Data points * Noisy data points Linear fit -80 _- -100 --- Logarithmicfit -100 I!II 0 -120 II II -120 -140 - noisefloor ' 1000a_2 OW 101 dB SPL RW 99 dB SPL ' -0.5 I · 0 I -140 I . · I 0.5 -80 I. -0.02 I i . . 0 I 0.02 ... . B.- . -0.5 0.5 - -- 0 I 0.5 -80 _ -100 I. -100 -120 I. -120 0 1000b_2 -140 OW 110 dB SPL RW 108 dB SPL -- -140 1-. II -0.5 0 0.5 ·. -0.02 I iI I. 0 -0.5 0.02 r . -0.5 . . . . .1 . . . . . . I I. . 0 . T. | 0. 5 0.5 -80 _ -80 -100 -100 0 -120 -140 -120 I 'I . . . -0.5 . I 1000c_2 OW 111 dB SPL RW 108 dB SPL . . . . 0 iV -140 -0.5 . (cycles) 0.5 i . -0.02 0 .I 0.02 ,q (cycles) · ........!:::., ! -0.5 0 0.5 Vr (cycles) Figure C-28: Simultaneous-stimuli measurement sets and model fits at 1000 Hz on Cat #2. 208 lvCl (dB re 1V) Zvcp (cycles) IVcpl (dB re 1V) 0.5 -80 -80 _ -100 -100 -120 -120 - o Datapoints _°"~n - Linear fit --- Logarithmic fit 0 )L -140 -140 ~;;;;~;;·............................. I 1 .... . -0.5 11. . . I,''1 0 .- 0.5 We.e....... ·...........·.....· ..... l I -0.02 I I 0.02 I -0.02 0 -0.5 -0.5 0.02 0 0.5 0.5 -80 -80 -100 -100 -120 10001_3 OW 109 dB SPL RW 113 dB SPL - -140 I :- - - -0.5 - II I - - - 0 - ..... I . ........................... l l I -0.02 -80 -80 -100 -100 -120 -120 1000a 3 - -120 II I 0.5 O 0 -140 .......................................... 0'.~ 0. O V I . -0.5 0.02 0 0.02 i I I .. ' . -0.5 0.5 . . . . 1.1 . .,! ! 0 0.5 0.5 0 0.5 0 0.5 0 110 dBSPL -140 111,,,,,,,,,,,,,,,,,,,,,,,,,,, -140 -0.5 0 0.5 -0.5 -0.02 0 0.02 -0.5 0.5 -80 - -80 -100 -100 -120 -120 -140 -140 0 .0..... l -0.5 0 vi (cycles) 0.5 § -0.02 I I 0 0.02 v (cycles) -0.5 -0.5 NV(cycles) Figure C-29: Simultaneous-stimuli measurement sets and model fits at 1000 Hz on Cat #3. 209 ZVcp (cycles) IVcpl (dB re 1V) lVcpI (dB re 1V) I,_ -80 -80 -100 -100 o Data points o Noisy data points -Linear fit --- Logarithmic fit U.b 0 -120 m -le -120 ! 111 a ISrL noisefloor .............................................. -140 , . -0.5 . . L I - - - 0 - -140 ! ! 0.5 -0.02 I 0 0 0.02 I -0.5 -. . -0.5 0.5 -80 -80 -100 -100 -120 -120 -140 -140 . . I. 0 ! . . II . . . 0.5 o 0 -0.5 -0.5 0 0.5 -0.02 0 0.02 -0.5 . . . 0 0.5 0 0.5 0 0.5 0.5 -80 -80 -100 -100 -120 -120 0 1000CL3 1 11 dB SPL -140 -140 I ! ! -0.5 0 0.5 ....... -0.02 -80 -80 -100 -100 -120 -120 -140 -140 0 -0.5 0.02 -0.5 0.5 0 -0.5 -0.5 0 xv(cycles) 0.5 -0.02 0 yV(cycles) 0.02 -0.5 v (cycles) Figure C-30: Simultaneous-stimuli measurement sets and model fits at 1000 Hz on Cat #3. 2i0 LVcp (cycles) IVcpl (dB re 1V) IVcpI (dB re 1V) n rU.D o Data points Linear fit Logarithmic fit -80 -80 --- -100 -100 -120 -120 -140 1000h_3 111 dB SPL noisefloor .w .................... * ......................... 0 -140 9I 1 -0.5 0 0.5 I I - -0.02 -80 -80 -- -100 -100 i- I I ' 0 0.02 -0.5 I . -0.5 0.5 .T- .. . . . I . . 1 . . . ' 0 0.5 0 -120 -120 1000i 3 111 dB SPL -140 -140 ,............................................... 1 . . .I.. -0.5 I I 0 0.5 -80 -100 -100 ~~_ ~ B ~~112dB SPL3 112 dB SPL I -140 -140 1.. .I -0.5 -120 , 0 r (cycles) . 0 0 0.02 "ap ......... ·.. II 0.5 I . I 0 -0.5 -0.5 0.5 I I 0 0.5 - e -120 ' -0.02 -80 L........ " ,................................... . .. · · · · I I . -0.02 0 v . 0 .... .. · ·........ -0.5 T -0.5 II - 0.02 (cycles) . .. . .. . .. I. II . . .. . 0 . .* I 0.5 v (cycles) Figure C-31: Simultaneous-stimuli measurement sets and model fits at 1000 Hz on Cat #3. 211 ZVcp (cycles) IVcplI (dB re 1V) lVcpl (dB re 1V) 0.5 -80 -80 -100 -100 120 -120 o Data points Linear fit --- Logarithmic fit 0 1000j3 noisefloor m -140 112 dB SPL T I -140 I I -0.5 0 0.5 -0.02 I I ·' ' 0 0.02 T -0.5 . -0.5 0.5 - . . . I . . . . I I 0 0.5 0 0.5 0 0.5 -80 _ -80 -100 -100 - 0 I -120 -120 1000k_3 -140 I I 112 dB SPL T -~ -140 . ............................................. , I . ! I ! ! 0.5 -0.02 . . . -- . -0.5 - - 0 l.................................. · II. , 0 I 0.02 -0.5 -0.5 0.5 -80 -80 -100 -100 -120 -120 _ 0 '4"%, 'L. -140 -140 .............................................. . . -0.5 . . . . I . 0 Nf (cycles) . . . I 0.5 ,i · -0.02 -0.5 , 0 yf (cycles) 0.02 -0.5 v (cycles) Figure C-32: Simultaneous-stimuli measurement sets and model fits at 1000 Hz on Cat #3. 212 LVcp (cycles) IVcpI (dB re 1 V) IVcpI (dB re 1 V) 0.5 -80 -80 -100 -100 -120 -120 -140 -140 Data points Linear fit --- Logarithmic fit o 0 ,Q_11·9__ ms.$ l~~~~~ l- ............................... i I 0 -0.5 _ -80 0.5 -0.01 -80 i--- 0 0.01 -0.5 -0.5 0.5 0 0.5 _ 1~~~~~~ ..I -100 -100 I- 0 -120 10Of_4 98 dB SPL -- ----------140 A..................... 0.5 I -0.5 0.5 0 -120 'CI -140 I -0.01 . . -0.01 0I 0 0.01 -0.5 0.01 -0.5 0 0.5 0 0.5 0.5 -80 -80 _ -100 -100 _ 0 -120 -120 1000a.4 106 dB SPL -140 . · . _ _ . . . . - I . - 0 -0.5 -140 .................................. I . - 0.5 . -0.01 . I 0 -0.5 0.01 -0.5 0.5 -80 -80 _ -100 I -100 _ 1OOOc_4 -120 ............................................ -140 -120 106 dB SPL -140 . . -0.5 -0.5 . . . . . . . I I0 . . 0 M (cycles) . . .I . . I 0. 5 -0.01 0.5 -0.01 ( · I 0 0 Nr(cycles) . I 0.01 0.01 -0.! i r -0.5 .... I .. 0 I 0.5 v (cycles) Figure C-33: Simultaneous-stimuli measurement sets and model fits at 1000 Hz on Cat #4. 213 IVcpl (dB re 1 V) ZVcp (cycles) lVcpl (dB re 1 V) 0.5 -80 o Data points -80 Linear fit - --- Logarithmicfit -100 -100 -120 -120 -140 -140 0 ..............................- 0.5 ..... 0 -0.5 0.5 I -0.01 I ! . . . ! 0 0.01 -0.5 -0.5 0.5 0 0.5 0 0.5 0 0.5 -80 _ -80 -100 _ -100 0 -120 -120 1000e_4 t106 dB SPL -140 ,....................................... I 0.5 . . . . I I-. - . . 0 - -140 . I -0.01 0 . 0. 5 . , 0.01 -0.5 -0.5 0.5 -80 l -80 - -100 -100 -- -120 -120 0 -140 i L L ..... .......... I... ...... .... . . ... * -0.5 0.5 0 v (cycles) -140 "-8" .................................. iI -0.01 . ' I I. I I 0 0.01 r (cycles) -0.5 -0.5 v (cycles) Figure C-34: Simultaneous-stimuli measurement sets and model fits at 1000 Hz on Cat #4. 214 IVcpl (dB re 1 V) (dB re 1 V) IvCl /Vcp (cycles) 0.5 -80 -80 o Data points Linear fit --- Logarithmic fit - -100 -100 0 _- -120 U 1000b 5 OW 102.5 dB SPL RW 102.5 dB SPL noisefloor -120 c~<CqlF -140 -140 . .. . . -0.5 . 0 . . . I I II 0.5 -0.01 0 . 0 , I . -0.5 0.01 -0.5 0 0.5 0 0.5 0.5 _ -80 -80 -100 -100 -120 -120 _ oo-ooooo . . . ................................................. -140 . . . -0.5 . 0 1000c_5 OW 103.2 dB SPL RW 101.9 dB SPL O t0awo 0 -140 . 1 . . . 0 : I I 0.5 -0.01 ,I . , . I 0 1 I -0.5 0.01 -0.5 0.5 -80 -80 -1 00 -100 -120 1000d_5 OW 103.7 dB SPL -- ................................................ . -0.5 - r -. 0 _ Ii RW101.2 dB SPL - -140 -120 -- . 7 T ' 1I I . . 0 V (cycles) ' 1 ' . -140 I1 1 0.5 1 I -0.01 ' 1 I I '. 0 yr (cycles) 1 I 0.01 -0.5 1- . I l l l l ! -0.5 -0.5 0 0.5 V (cycles) Figure C-35: Simultaneous-stimuli measurement sets and model fits at 1000 Hz on Cat #5. The sum of the magnitudes of IPowi and IPRwl was held constant: IPowl + IPRWI = 5.3 Pascals. 215 ZVcp (cycles) IVcpl (dB re 1 V) IVcpl (dB re 1 V) 0.5 o Data points -80 -80 -100 -100 Linear fit --- Logarithmic fit o 4 --- 0 1000e_5 OW 104.4dB SPL RW 100.5 dB SPL -120 -140 . . . . . . .I .. .. 0 -0.5 ..................................... -140 noisefloor ' -120 0 .. .. I... ,-- .-- · 0.5 -0.01 0.5 -0.01 0 , -0.5 0.01 - -( . * . . - . - I I - - - - 0 0.5 0 0.5 0.5 -80 -80 -100 -100 -120 -120 0 OW 103.0 dB SPL RW 102.3 dB SPL -140 -140 I -0.5 0 0.5 v (cycles) -0.01 I I I 0 -V (cycles) I 0.01 -0.5 -0.5 V (cycles) Figure C-36: Simultaneous-stimuli measurement sets and model fits at 1000 Hz on Cat #5. The sum of the magnitudes of IPowI and IPRwI was held constant: IPowl + IPRwl = 5.3 Pascals. 216 IVcpl (dB re 1 V) LVcp (cycles) IVcpl (dB re 1 V) 0.5 -80 _ o Datapoints -80 -100 -100 -120 -120 * Noisy data points Linear fit --- - Logarithmic fit 0 noisefloor 90 dB SPL .....---------..-------.......................- -140 r0 ., . . . -0.5 . . 0. -140 -l I I -0.01 0 0.01 I 1 * 0 0.5 -0.5 0 -0.5 0.5 0.5 -80 _ -80 -100 -100 -120 -120 -140 -140 m . . * I _ 0 0 .. 0 0.5 ....I . . -0.5 w- ............ I .I -0.01 0 -0.5 0.01 - - . - . ;Zi . -0.5 i0.!5 0 0.5 -80 -80 _- -100 -100 I- -120 -120 0 1000k_5 § |95 -~ - dB SPL -140 -140 .... . -0.5 . - - - . .... - I _D,_ORM-- - 0 .. I - - ' ' . ' _ I 0 5 I , ' I I I -0.01 0 ! 1 1 - I - - -, " -0.5 -0.5 0 0.5 -0.5 0 0.5 0.01 0.5 -80 -80 -100 -100 -120 -120 -140 - 0 '' -140 . -0.5 - . . I . 0 Mf (cycles) . 1 4_ 0.5 -0.01 , I 0 x (cycles) -0.5 0.01 Mf (cycles) Figure C-37: Simultaneous-stimuli measurement sets and model fits at 1000 Hz on Cat #5. 217 IVcplI (dB re 1 V) IVcpl (dB re 1 V) ZVcp (cycles) - 0.5 -80 -80 -100 -100 -120 -120 - 0 L -140 -140 . l I . . . 0 -0.5 0.5 05 -0.5 I -0.01 0 0 . . . I . . 0 . . I 0.5. 0 0.5 -0.5 0.01 0 0.5 0.5 -80 K -80 -100 -100 -120 -120 0 -d0t--' -140 -140 I 0 -0.5 0.5 III I. -0.01 ', I . 0 III -0.5 -0.5 0.01 -0.5 0.5 -80 -80 _ -100 -100 _ -120 -120 -140 1000m 5 105 dB SPL ........... ... , ..... , ... I.... 0 0.5 4 I -140 1I . . . .. II .. .. .. .. II -0.5 0 '1 . I I -0.5 . I -0.01 0 -0.5 0.01 0 . . . . 0 0.5 0.5 -80 -80 -100 -100 -120 -120 -140 -140 _ _~ 0 00 6,,o o ,, <5"' . :. -0.5 0 f (cycles) 0.5 -0.01 . 0 f (cycles) i 0.01 -0.5 -0.5 0 y (cycles) 0.5 Figure C-38: Simultaneous-stimuli measurement sets and model fits at 1000 Hz on Cat #5. 218 IVcpl (dB re 1 V) ZVcp (cycles) IVcpl (dB re 1 V) 0.5 I -8( 3 -80 -10(0 -100 0 . -12(0 - Data points Linearfit --- Logarithmic fit o 1000h_5 110 dB SPL noisefloor -14( ) ....... 'I . . . -0.5 -140 . . -120 I 1 1 1 1 1 I 0 0. 5 . -0.01 . A 0 -0.5 0.01 0 -0.5 0.5 ~ n= U.O -8C -80 -10( -100 -12( -120 Bm 0 10001_5 110 dB SPL -14( ) . .... ...-- . . ..... - . . I -~~~~~~~~~~~~~~~~~ -140 i::::1 -VU. 0 -0.5 0.5 -0.01 0 0.01 ' -0.5 · .· I . · 0 I I 0.5 0.5 -80 -80 -100 -100 Vr -120 -140 1000i_5 115 dB SPL 3__............................................ . -0.5 . . . I xV (cycles) 0 - -140 . , . I ' . . 0 . -120 -7-""OF . . I 0.5 I I -0.01 I I 0 I yr (cycles) 1 0.01 . .. :."'.!. ." . a -0.5 -0.5 0 N (cycles) 0.5 Figure C-39: Simultaneous-stimuli measurement sets and model fits at 1000 Hz on Cat #5. 219 -80 I e o Data points Linear fit --- Logarithmic fit -80 -100 -100 -f -120 -120 _- 10OOr_5 115 dB SPL noisefloor -140 - - --.-0.5. . . . 0. . . . . 0.5 -0.5 0 ZVcp (cycles) IVcpl (dB re 1 V) IVcpl (dB re 1 V) 0oot V.0 EI 0 ee-0- -140 a lI -0.01 0 1I -0o5 _._ 1 0 -0.5 0.01 0.i5 0.5 -80 _ -80 -100 0L -100 ·F-iP·9"Q 0 -120 -120 -140 -140 ..................................... 1 -0.5 0 N' (cycles) 0.5 -0.01 · I I 0 0.01 V (cycles) -0.5 i -0.5 ' ' ' ' I a 0 ' ' +- I 0.5 Nf (cycles) Figure C-40: Simultaneous-stimuli measurement sets and model fits at 1000 Hz on Cat #5. 220 IVcpI (dB re 1 V) IVcpl (dB re 1 V) Z Vcp (cycles) 0.5 -80 -80 -100 -100 00 o Data points - Linear fit --- Logarithmicfit 0 -120 -120 b 1000a6 I -~ 1U . noisefloor -140 -140 I .· . .! . I -0.5 3·b ODL OrL . . . . 0 ........ I 0.5 I · -0.01 h1 , I 1 0 0.01 I· , -0.5 . . - 0.5 . . . 0 . 0. 5 0.5 -80 _ -80 --- -100 -100 -120 -120 IOO0bL6 114 dB SPL ~~~~~~~~~i~ 0 i -140 -140 . . . . -0.5 . . ! . . 0 v (cycles) . . I 0.5 _ -0.01 0 Ni (cycles) " " 111 -0.5 I I 0.01 -0.5 0 0.5 v (cycles) Figure C-41: Pre-TTX simultaneous-stimuli measurement sets and model fits at 1000 Hz on Cat #6. 221 IVcpI (dB re 1 V) Z Vcp (cycles) IVcPl (dB re 1 V) V.0c_ _ -80 -80 -100 -100 -120 -120 _ 1000j_6 ~~8OdB SPL 80dBSL - noisefloor ............. -140 ....................... ' . - - . - . - . . -0.5 I - - 0 0.5 -- - Logarithmicfit 0 /L, -140 -0.5 is:2~; I -. I o Data points o Noisy data points Linear fit -0.01 0 . . · .r . . . .. -0.5 0.01 . . . . . . . . . . 0 0.5 0.5F -80 -80 _ -100 -100 _ -120 -120 _ -140 -140 ........v e ................... 0- 0 I -0.01 -0.5 0 0.5 -0.01 I I 0 0.01 0 0.01 L --0.5 I l l -l -0.5 l I l l 0 0.5 0.5 -80 -80 _- -100 -1 00 _0 -120 d -120 98 dB SPL -140 ..................... 'I -0.5 . . . -140 I...................... . . . . 0 v (cycles) . I I I. 1.I0.01 -0.01 0 0.01 I 0.5 v (cycles) -0.5 l l 0.5 l l l II lII l l 0 l l I l I 0.5 ' (cycles) Figure C-42: Post-TTX simultaneous-stimuli measurement sets and model fits at 1000 Hz on Cat #6. 222 IVcpl (dB re 1 V) IVcpl (dB re 1 V) Vcp (cycles) L 0.5 -80 o Data points -80 i --- Linear fit Logarithmic fit -100 100 120 1000t_6 98 dB SPL -140 _ noisefloor l l I-0.5 l l l l l l I l 0 -0.5 l 0 -120 -140 l I 0.5 -0.01 · I -0.5 i I -80 _ . 0 0.01 _ -100 -120 -120 . -0.5 0.5 - .. -80 -100 I II . II . . . 0 0.5 dI 0 1000h_6 100 dB SPL e4a -140 -140 - -0.5 - - - I - - - - 0 -0.5 I 0.5 -0.01 -80 -80 -100 -100 -120 -120 1000q.-6 104 dB SPL -140 -140 - -! -0.5 0 - - Mv(cycles) - - II ! 0.5 0 0.01 I . . .e . . 4 .. -0.5 0.5 I I - . . . 0 0.5 0 0.5 0 ft%000 ..................................... I. 0 II -0.01 I ! vl (cycles) II 0.01 -0.5 -0.5 s (cycles) Figure C-43: Post-TTX simultaneous-stimuli measurement sets and model fits at 1000 Hz on Cat #6. 223 1vcI n I: U.:: _- -80 -80 _; -100 -100 -120 -120 -140 Z Vcp (cycles) IVcpI (dB re 1 V) (dB re 1 V) 10009g_6 110 dB SPL T noisefloor - ......l l I .5 -0.5 o Data points f~~~' --- -140 l I l l 0 A _ #S# dc,1 _ Linear fit Logarithmic fit 0 It _~~~~~~~~~~~~~~~~~I 10 ..................................... I I I 0.5 -0.01 0 , , I 0.01 -0.5 a _. -0.5 0.5 . -. . a - - - - I 0 0.5 0 0.5 0 0.5 -80 _ -80 -100 -100 -120 -120 -140 140 0 - I .* -0.01 . -0.5 0 0.5 'I 0 , I 0.01 -0.5 -0.5 0.5 -80 I- -80 -100 19&I -100 -120 1000k_6 120 dB SPL 0 -120 i_ -140 -140 .............. I -0.5 . . . . I ............ 0 N'(cycles) I 0.5 I I I -0.01 0 -0.5 · 0.01 v (cycles) -0.5 Nr(cycles) Figure C-44: Post-TTX simultaneous-stimuli measurement sets and model fits at 1000 Hz on Cat #6. 224 (dB re 1V) IVCPI IVcpI (dB re 1V) ZVCP (cycles) 0.5 -80 _ -80 -100 -100 -120 -120 o Data points _ --- Linear fit Logaithmicfit 0 'L -140 ....................... 'I. .; .. .. -0.5 ;. . ·.............. . ; I X I . -140 ·........ . . . 1 0 . 1.1 . I I 0.5 . I * I -0.01 0 I * I 0.01 -0.5 -0.5 0.5 0 0.5 -80 _' -80 --- -100 -100 -120 -120 _- -140 -140 A 0 JAA I -0.5 0 v (cycles) 0.5 . -0.01 I 0 Mi (cycles) I 0.01 -0.5 -- -- --. -- -- -- -- -- - -0.5 I I 0 0.5 -i (cycles) Figure C-45: Pre-TTX simultaneous-stimuli measurement sets and model fits at 1000 Hz on Cat #7. 225 II"-U"V··"-~"~"~1~1"^--111`-"11- IVcpl (dB re 1V) ZVcp (cycles) IVcpl (dB re 1V) . U. -80 -80 -100 -100 -120 I -140 I - o Data points Noisy data points Linear fit - -- Logarithmic fit 140 II I1 · * I -0.5 0. 5 0 r 0 -120 _ I , -0.01 I I ' I 0 0.01 -"t- -0.5 -rr . -0.5 . · . . . I I I 0.5 0 0.5 -80 I- -8( 3 -10(0 -100 I- -12( -120 0 -14(0 -0 ............. -140 ........................... -0.5 °-5 0 1 -0.01 1 1 0 1~ 0.01 -0.5 . I . . . I . .. __" . I I -0.5 0.5 0 0.5 0 0.5 0 0.5 -80 _- -81 O _ -10( ..................................... 1 O -100 _0 -120 -12( "110 4O -14( jF__;:··1 . ' -0.5 I · . L . 0 -140 0.5 ..................................... EI . I I -0.01 0 I I , . I 0.01 -0.5 -0.5 0.5 -80 -80 _ -100 -100 _ -120 -120 -140 1000f 7 119 dB SPL ................................................ - - -0.5 - - - -II l - - - 0 v (cycles) - II I 0.5 -140 0 l · I·, -0.5 ..................................... I .! -0.01 0 0.01 v (cycles) -0.5 Nf (cycles) Figure C-46: Post-TTX simultaneous-stimuli measurement sets and model fits at 1000 Hz on Cat #7. 226 Bibliography Allen, J. B. (1985). "Cochlear modeling," IEEE ASSP 2(1):3-29. B4kesy, G. v. (1936a). "Zur Physik des Mittelohres und iiber das Hbren bei fehlerhaftem Trommelfell," Akust. Zeits 1:13-23 (pp. 104-115 in Bekesy, 1960). Bekesy, G. v. (1936b). "Uber die H6rschwelle und Fiihlgrenze langsamer sinusf£rmiger Luftdruckschwandungen," Ann. Physik 26:554-566 (pp. 257-267 in B6k4sy, 1960). Bekesy, G. v. (1960). Experiments in Hearing. McGraw-Hill, New York. Edited by E. G. Wever. Dolan, D. F., Xi, L., and Nuttall, A. L. (1989). "Characterization of an EPSP-like potential recorded remotely from the round window," J. Acoust. Soc. Am. 86(6):21672171. Gotay-Rodriquez, V. M. and Schuknecht, H. F. (1977). tympanomastoidectomy," Laryngoscope 87:522-528. "Experiences with type IV Kaplan, M. S., Szaro, B. G., and Weiss, T. F. (1983). "Components of the cochlear electric responses in the alligator lizard," Hearing Research 12:323-351. Lee, K. and Schuknecht, H. F. (1971). "Results of tympanoplasty and mastoidectomy at the Massachusetts Eye and Ear Infirmary," Laryngoscope 81:529-543. Merchant, S. N., Rosowski, J. J., and Ravicz, M. E. (1995). "Middle-ear mechanics of type IV and type V tympanoplasty II. Clinical analysis and surgical implica- tions,"Am. J. Otolarngol.in press. Nash, J. (1979). Compact Numerical Methodsfor Computers: linear algebraand function minimisation, chapter 14, pages 141-152. John Wiley & Sons, New York. Peake, W., Rosowski, J. J., and Lynch, T. J. (1992). "Middle-ear transmission: Acoustic versus ossicular coupling in cat and human," Hearing Research57:245-268. Pickles, J. 0. (1988). An Introduction to the Physiology of Hearing. Academic Press, 2 edition. Press, W. H., Teukolsky, S. A., Vetterling, W. T., and Flannery, B. P. (1992). Numerical Recipes in C. Cambridge University Press. Rosowski, J. J., Merchant, S. N., and Ravicz, M. E. (1995). "Middle-ear mechanics of type IV and type V tympanoplasty I. Model analysis and predictions," Am. J. Otolarngol. in press. 227 Shera, C. A. and Zweig, G. (1992). "An empirical bound on the compressibility of the cochlea," J. Acoust. Soc. Am. 92(3):1382-1388. Wever, E. G. and Lawrence, M. (1950). "The acoustic pathways to the cochlea," J. Acoust. Soc. Am. 22(4):460-467. Wever, E. G., Lawrence, M., and Smith, K. R. (1948). "The middle ear in sound conduction," Archives of Otolaryngology48:19-35. Wullstein, H. (1956). "The restoration of the function of the middle ear, in chronic otitis media," Ann. Otol. Rhinol. Laryngol. 65:1020-1041. Zwislocki, J. (1965). "Analysis of some auditory characteristics," in Luce, R. D., Bush, R. R., and Galanter, E., editors, Handbook of Mathematical Psychology, volume 3, chapter 15, pages 1-97. John Wiley & Sons, New York. fa3q - "-8 228