CLINICAL VALIDATION
OF THE 3 SERIES POWER PLUS BTE
Overcoming SNR Loss for Individuals with Severe-to-Profound Hearing Loss
Alyson Gruhlke, Au.D. & Elizabeth Galster, Au.D.
Fitting individuals with severe-to-profound
sensorineural hearing loss can pose various
challenges in the clinic.
One challenge is restoring audibility in the high
frequencies. Voiceless consonants, such as /s/, which
are important for clarity and understanding, fall into the
frequency range of 6.3 to 8.8 kHz (Stelmachowicz, Lewis,
Choi & Hoover, 2007). Restoring audibility for these highfrequency speech sounds is further complicated by the
natural high-frequency roll-off of microphones and receivers
used in today’s hearing aids (typically 4,000 Hz and
above) (Dillon, 2001). Additionally, providing sufficient
gain in the high frequencies to restore audibility may result
in feedback. In total, these issues may affect the clinician’s
ability to allow access to high-frequency speech cues in
patients with severe-to-profound hearing loss. Through use
of powerful hearing devices that provide ample amounts of
gain, frequency lowering technology, such as Spectral iQ,
and advanced feedback cancellation algorithms, restoring
audibility for individuals with severe hearing loss is a much
more realistic goal now than it was even just several years
ago (Galster, Valentine, Dundas & Fitz, 2011).
Despite restoring audibility, the complaint of difficulty
understanding speech in background noise often persists,
thus leading to a second challenge of improving signalto-noise ratio (SNR) loss. SNR loss is defined as “the dB
increase in SNR required for 50 percent correct word
recognition, over the average SNR required by those with
normal hearing to achieve a 50 percent correct score”
(Killion, 1997). A positive relationship between audiometric
loss and SNR loss has been documented, such that, on
average, SNR loss increases with worsening hearing
Clinical Validation of the 3 Series Power Plus BTE
Reprinted from Innovations: Volume 4, Issue 2, 2014
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0
Hearing Threshold Level (dB HL)
10
20
30
40
50
60
70
80
90
100
110
120
100
1K
10K
Frequency in Hertz (Hz)
Left Mean
Figure 1: The 3 Series Power Plus BTE.
loss. SNR loss can be measured with tests such as
the Hearing-in-Noise-Test (HINT) or the QuickSIN
(Nilsson, Soli & Sullivan, 1994; Killion, Niquette,
Gudmundsen, Revit & Banerjee, 2004). Use of
directional microphones is a widely accepted method
for improving SNR in situations with background
noise. In addition to directional hearing aids, wireless
accessories are another option for overcoming the
negative effects of severe and profound SNR loss,
which is defined by Killion and Niquette (2000) as
SNR loss ranging from 11–20 dB.
Unfortunately, patients with severe-to-profound
hearing loss and severe and profound SNR loss may
avoid difficult listening situations, especially those in
which directionality and wireless accessories are of
greatest benefit (e.g., restaurants, phone). In order
to accommodate the everyday listening needs of this
patient population, especially in adverse listening
conditions, Starkey Hearing Technologies now offers
a 3 Series™ Power Plus* behind-the-ear (BTE) hearing
aid with a matrix of 138/80 and features such as
Spectral iQ, Voice iQ2, and full wireless compatibility.
This article describes the clinical validation of the
3 Series Power Plus BTE hearing aids, pictured in
Figure 1, with particular focus on directional benefit
and use of wireless accessories among a group of
experienced hearing aid users with severe-to-profound
hearing loss.
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Clinical Validation of the 3 Series Power Plus BTE
Right Mean
Maximum
Minimum
Figure 2: Mean audiometric thresholds for right and left ears
are displayed in red and blue lines, respectively. Black lines
represent group minimum and maximum thresholds.
Fittings and Real-Ear
Measurements
Twelve individuals, three females and nine males,
participated in the clinical trial of the 3 Series
Power Plus BTE hearing aids. The study consisted
of a minimum of four visits over a total of six to
eight weeks. The mean age of all participants was
71.1 years, with a range of 45 to 88 years. Mean
audiometric data, as well as group minimum and
maximum thresholds, are shown in Figure 2. Prior
to the start of the clinical trial, the QuickSIN was
completed under headphones on all participants
and administered according to test instructions
(Etymotic Research, Inc., 2006). Mean SNR loss
of all participants (24 ears) was 16.5 dB with a
standard deviation of 4.7 dB, indicating severe or
profound SNR loss for the majority of participants.
Participants were fit with standard tubing and
earmolds, and the hearing aids were Best Fit to
Starkey Hearing Technologies’ proprietary e-STAT®
targets at the initial session (Scheller & Rosenthal,
2012). REAR measurements were then completed
using the Audioscan Verifit system, with a purpose of
measuring the output of the devices in the ear canal
and ensuring audibility. The International Speech
Test Signal (ISTS) stimulus was used for all real-ear
measurements and was presented at levels of 50 dB,
Reprinted from Innovations: Volume 4, Issue 2, 2014
100
8
6
4
80
dB SNR
REAR (dB SPL)
90
70
3.6
2
0
-0.7
-2
-4
60
100
10K
1K
Frequency in Hertz (Hz)
Front Response
Null Response
-6
Omnidirectional
Directional
Test Conditions
Figure 3: Mean real-ear aided responses in directional
mode from the front and null are displayed in blue and red,
respectively.
Figure 4: Mean HINT data for both omnidirectional and
directional conditions are displayed in the figure above.
Error bars represent one standard deviation. Mean score with
directional mode was significantly better than mean score
with omnidirectional mode (p<0.001).
65 dB and 75 dB SPL through a speaker positioned at
0° azimuth (Holube, Fredelake, Vlaming & Kollmeier,
2010). Additionally, an 85 dB SPL pure-tone sweep
was presented. The gain and frequency response
of the devices were adjusted as needed at each
subsequent visit in order to optimize listening comfort
for each participant. In addition to measuring REARs
with the 3 Series Power Plus BTEs, the same REAR
measurements were made with the participants’ own
devices to document the fitting parameters of those
devices. Measurements of on-ear directivity were also
completed with the 3 Series Power Plus BTEs at the
initial session using the Audioscan Verifit system. With
the hearing devices set to directional mode, a front
speaker was positioned at 0° azimuth and a back
speaker was positioned at the approximate null angle
of the directional response. The Verifit directional
stimulus was presented at a level of 65 dB SPL and
recordings were made from the front and the null
simultaneously. Figure 3 shows mean REAR (dB SPL)
as a function of frequency, with the response from the
front (blue line) and the response from the null (red
line) as the parameters displayed within the figure.
At the peak, the average response from the front is
16.5 dB SPL greater than the response from the null,
indicating that the directional system was performing
as expected, attenuating signals from the null.
Speech-in-Noise Testing
Clinical Validation of the 3 Series Power Plus BTE
Participants completed the HINT to evaluate directional
benefit on a speech-in-noise task. The HINT is a
standardized speech test that adaptively arrives at the
SNR required for correct repetition of 50 percent of
the sentences presented in a background of competing
speech-shaped noise at a fixed level of 65 dB SPL
(Nilsson, Soli & Sullivan, 1994). The level of speech
adapts based on participant response, and the score
is recorded as a signal-to-noise ratio (dB SNR). Unlike
the QuickSIN, the unaided condition for the HINT
could not be completed due to the severity of the
participants’ hearing losses and the output limitations
of the hardware used to present the stimuli. Twenty
sentences were administered per condition and two
conditions (omnidirectional and directional) were
completed in a randomized order for each participant.
Figure 4 displays the HINT scores (dB SNR) for those
two conditions. The error bars represent one standard
deviation. In summary, participants performed
significantly better with directionality when compared to
the omnidirectional mode (p<0.001), indicating that the
directional system of these hearing aids performed as
expected and resulted in significant directional benefit.
These results support the theory that directionality is a
valuable tool in overcoming SNR loss.
Reprinted from Innovations: Volume 4, Issue 2, 2014
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Figure 5: The SurfLink Mobile is pictured in front and
the SurfLink Media is pictured in back.
Wireless Accessories
SURFLINK MOBILE:
In addition to testing the hearing devices, eight
participants were also asked to evaluate either
SurfLink® Mobile or SurfLink Media, both pictured
in Figure 5, with the 3 Series Power Plus BTE
devices. SurfLink Mobile has the capability of
being used as a hearing aid remote control, a
device for transmitting phone calls and streaming
media and a remote microphone. SurfLink Media
is used specifically for streaming a television
audio signal to the hearing aids. The commonality
between these two devices lies in the wireless
transmission of the audio signal to both hearing
aids via 900 MHz wireless technology, which
improves the SNR for the listener through
elimination of the distance between the sound
source and the hearing aid microphones.
Participants were asked to complete multiple
questionnaires regarding sound quality and
speech understanding while using these devices.
On a five-point scale, ranging from very poor
to very good, seven out of eight participants
rated the sound quality of the streamed audio
signal from either device as good or very good.
Participant comments regarding SurfLink Mobile
and SurfLink Media are provided to the right.
“It works great for my cell phone and computer.
I can hear and understand voices.”
4
Clinical Validation of the 3 Series Power Plus BTE
“Phone conversations are easier to understand.”
“The SurfLink Mobile makes hearing easier.”
“I would absolutely recommend the SurfLink Mobile.
It is a great hearing tool.”
“My ability to understand on the phone is better and
you don’t have to keep the phone in the ‘sweet spot.”
SURFLINK MEDIA:
“The ability to stream and hear other conversations
is great.”
“You do not have to wear a headset, which is
extremely nice.”
“I like the streamer very much. It is very easy for me
to hear the television at the same time there is
someone else watching with me.”
“I am able to process what is said much better now.”
Reprinted from Innovations: Volume 4, Issue 2, 2014
Overall Hearing Aid Satisfaction
Final Thoughts
Clinical trial results suggest that the directionality and
full wireless compatibility provided by the 3 Series
Power Plus BTE can help those suffering from the
negative effects of severe and profound SNR loss.
Furthermore, this hearing aid allows individuals with
severe-to-profound hearing loss the opportunity to stay
active in everyday listening situations, even in the
most challenging environments.
* 3 Series is a Starkey brand name.
3 Series Power Plus BTEs
5
Rating (1= worst, 7=best)
Participants were asked to complete the DeviceOriented Subjective Outcome Scale (DOSO) once
at the beginning of the study, answering questions
about their own hearing aids, and a second time at
the conclusion of the study regarding the test devices.
The DOSO was developed by Cox, Alexander
and Xu (in press) and is designed to examine six
subscales (speech cues, listening effort, quietness,
pleasantness, convenience and use) related to the
hearing devices. Results are provided in Figure 6. The
error bars represent one standard deviation. Results
indicate significantly better (p<0.001) subjective
outcomes on all subscales with the 3 Series Power
Plus BTEs relative to the participants’ own devices.
Two questions on the DOSO specifically relate
to hearing in the presence of background noise:
1) “How good are the hearing aids at keeping
background noise to a minimum?” and 2) “How
good are the hearing aids at cutting out background
noise in a restaurant?” Mean responses on these two
questions indicated significantly better performance
(p<0.05 and p<0.01, respectively) in situations with
background noise with the 3 Series Power Plus BTEs
when compared to performance with the participants’
own devices.
Own Devices
7
5
5.9
4
5.4
5.4
5.1
3
4.8
5.0
4.4
3.9
2
1
3.2
Subscale
3.4
Listening Effort
Pleasantness
Quietness
Convenience
Subscale
Figure 6: Mean DOSO data for five subscales are shown for
participants’ own devices and the 3 Series Power Plus BTEs in
blue and red, respectively. Error bars represent one standard
deviation. Mean ratings with the 3 Series Power Plus BTEs
were significantly greater than mean ratings of participants’
own devices for all subscales (p<0.001).
References
Cox, R.M., Alexander, G.C., & Xu, J. (In press). Development of the DeviceOriented Subjective Outcome (DOSO) Scale. Journal of the American Academy
of Audiology.
Dillon, H. (2001). Hearing Aids. Australia: Boomerang Press.
Etymotic Research, Inc. (2006). QuickSIN Speech-in-Noise Test Version 1.3.
Elk Grove Village, Illinois.
Galster, J.A., Valentine, S., Dundas, J.A., & Fitz, K. (2011). Spectral IQ: Audibly
improving access to high-frequency sounds. Starkey Hearing Technologies,
Technology Paper.
Holube, I., Fredelake, S., Vlaming, M., & Kollmeier, B. (2010). Development
and analysis of an International Speech Test Signal (ISTS). International Journal
of Audiology, 49(12), 891-903.
Killion, M.C. (1997). SNR Loss: “I Can Hear What People Say, but I Can’t
Understand Them.” The Hearing Review, 4(12), 8-14.
Killion, M.C. & Niquette, P.A. (2000). What can the pure-tone audiogram tell us
about a patient’s SNR loss? The Hearing Journal, 53(3), 46-53.
Killion, M.C., Niquette, P.A., Gudmundsen, G.I., Revit, L.J., & Banerjee, S. (2004).
Development of a quick speech-in-noise test for measuring signal-to-noise ratio in
loss in normal hearing and hearing-impaired listeners. Journal of the Acoustical
Society of America, 116(4), 2395-2405.
Nilsson, M., Soli, S.D., & Sullivan, J.A. (1994). Development of the hearing in
noise test for the measurement of speech reception thresholds in quiet and in noise.
Journal of the Acoustical Society of America, 95, 1085-1099.
Scheller, T. & Rosenthal, J. (2012). Starkey Hearing Technologies’ e-STAT Fitting
Formula: The rationale behind the rationale. Innovations, 2(2), 41-45.
Stelmachowicz, P.G., Lewis, D.E., Choi, S., & Hoover, B. (2007). Effect of stimulus
bandwidth on auditory skills in normal-hearing and hearing-impaired children. Ear &
Hearing, 28(4), 483-494.
Clinical Validation of the 3 Series Power Plus BTE
Reprinted from Innovations: Volume 4, Issue 2, 2014
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