Evaluating speech detection in aided infants and
estimating pure tone thresholds in unresponsive
adults: Auditory-evoked cortical potentials
Harvey Dillon, Bram Van Dun, Lyndal Carter, Kirsty Gardner-Berry
HEARing CRC
National Acoustic Laboratories (NAL)
ASA, Audiology Now!
With thanks to John Seymour, Suzanne Purdy, Maryanne Golding
www.hearingcrc.org
NAL: Dillon, Van Dun, Carter, Gardner-Berry
The need for a new
measurement tool
NAL: Dillon, Van Dun, Carter, Gardner-Berry
Evaluation of aided functioning in infants
Universal new born screening
Early fitting of hearing aids
Need for an evaluation method
Confirmation
of fitting
NAL: Dillon, Van Dun, Carter, Gardner-Berry
Fine-tuning
needed
Cochlear
implant
needed
So baby, how does it sound?
Objective hearing aid
evaluation for:
• young infants
• difficult-to-test
people
NAL: Dillon, Van Dun, Carter, Gardner-Berry
Why the rush?
Language ability 6 months after implantation
Covariate means:
MonFit: 10.97917
Language at 6 months after implantation
Wilks lambda=.71507, F(2, 28)=5.5785, p=.00914
120
CA6P_AC
CA6P_EC
110
100
90
80
70
60
PLS-4 standard scor
50
40
< 12m
12m +
Implant age category
NAL: Dillon, Van Dun, Carter, Gardner-Berry
Early intervention leads to better language
development at 6 months after fitting (n=90)
Significant effect of age of fitting: p = 0.001*
Covariate means:
F6AV3FA: 57.11296
(Computed for covariates at their means)
Vertical bars denote 0.95 confidence intervals
Pres: NAL
120
Pres: DSL
A6P_AC
A6P_EC
110
100
90
80
PLS-4 standard scores
70
60
< 6m
>= 6m
< 6m
>= 6m
Fitting age category
NAL: Dillon, Van Dun, Carter, Gardner-Berry
Early intervention leads to better language
development at 6 months after fitting (n=90)
Significant effect of age of fitting: p = 0.001*
Covariate means:
F6AV3FA: 57.11296
(Computed for covariates at their means)
Vertical bars denote 0.95 confidence intervals
Pres: NAL
120
Pres: DSL
A6P_AC
A6P_EC
110
100
90
80
PLS-4 standard scores
70
60
< 6m
>= 6m
< 6m
>= 6m
Fitting age category
NAL: Dillon, Van Dun, Carter, Gardner-Berry
Why use cortical responses?
NAL: Dillon, Van Dun, Carter, Gardner-Berry
Why cortical responses to evaluate hearing
aid fitting in infants?
• Reliably present in awake young infants
• More likely to correlate well with
perception
• Can be elicited by a range of speech
phonemes – close to desired outcomes
• Stimuli handled reasonably by hearing aids
• Can be very frequency specific if needed
NAL: Dillon, Van Dun, Carter, Gardner-Berry
Overview of Learning Lab
Cortical responses
–
–
–
Where from
Development with age
Typical waveforms
Measuring infant cortical responses – video
Research results
–
–
–
–
–
Effect of auditory experience
Cortical responses to different stimuli
Automatic detection of cortical responses
Sensation level, hearing loss, and noise
Relationship to functional hearing ability
Clinical applications
– Estimating hearing thresholds in adults – live demo
– Assessing speech audibility for infants
– Case studies
Future possibilities
NAL: Dillon, Van Dun, Carter, Gardner-Berry
FUNDAMENTALS
OF
CORTICAL
RESPONSES
NAL: Dillon, Van Dun, Carter, Gardner-Berry
Corpus callosum
Perception
Auditory System:
Central Pathways
Cortex: Complex detection
Medial
geniculate
nucleus
Thalamus: Auditory and
visual map integrated,
relayed to cortex
IC: Form full spatial map,
Parallel processing paths join,
History dependent
VNLL: Fed by contralateral CN
Lateral lemnisci
Plastic, e.g following
cochlear ablation
Sorting, comparing and categorizing
SC: Visual spatial map
MSO: Detect interaural time
LSO: Detect interaural level
AVCN: Frequency analysis,
PVCN: Timing well preserved
DCN: Inhibitory circuits, pinna cue
detection?
Parallel processing
Needs to be fed to develop & maintain
NAL: Dillon, Van Dun, Carter, Gardner-Berry
Corpus callosum
Perception
Auditory System:
Central Pathways
Cortex: Complex detection
Medial
geniculate
nucleus
Thalamus: Auditory and
visual map integrated,
relayed to cortex
IC: Form full spatial map,
Parallel processing paths join,
History dependent
VNLL: Fed by contralateral CN
Lateral lemnisci
Plastic, e.g following
cochlear ablation
Sorting, comparing and categorizing
SC: Visual spatial map
MSO: Detect interaural time
LSO: Detect interaural level
AVCN: Frequency analysis,
PVCN: Timing well preserved
DCN: Inhibitory circuits, pinna cue
detection?
Parallel processing
Needs to be fed to develop & maintain
NAL: Dillon, Van Dun, Carter, Gardner-Berry
The end of the road
NAL: Dillon, Van Dun, Carter, Gardner-Berry
Auditory cortex orientation
NAL: Dillon, Van Dun, Carter, Gardner-Berry
Auditory cortex orientation
NAL: Dillon, Van Dun, Carter, Gardner-Berry
Auditory cortex orientation
NAL: Dillon, Van Dun, Carter, Gardner-Berry
+
+
Hudson, 2009
NAL: Dillon, Van Dun, Carter, Gardner-Berry
Auditory cortex and current sources
Sussman et al
(2008)
NAL: Dillon, Van Dun, Carter, Gardner-Berry
Cortical responses in adults with
normal hearing
NAL: Dillon, Van Dun, Carter, Gardner-Berry
Adult
P2
5.0
2.5
N1
P1
µV
0.0
-2.5
0
100
200
300
400
500
600
NAL: Dillon, Van Dun, Carter, Gardner-Berry
Adult grand mean waveforms at Cz
+
1.25µV
Speech
---
Tones
-100
0
100
200
Time (ms)
300
400
500
NAL: Dillon, Van Dun, Carter, Gardner-Berry
Development of cortical
responses with age
NAL: Dillon, Van Dun, Carter, Gardner-Berry
Infants
P
10
µV
5
N
0
-5
-100
0
100
200
300
ms
400
500
600
NAL: Dillon, Van Dun, Carter, Gardner-Berry
Maturational
effects on
cortical evoked
response
morphology
• N=8-16 per grand mean
• Cz site
• stimulus = 10 click train,
2 ms ISI @ 65 dB SL
• rate = 1.3/s
NAL: Dillon, Van Dun, Carter, Gardner-Berry
Ponton et al (2000)
2 years
12 years
I
II

 Fewer
neuro-filaments in
young children,
especially in more
superficial cortical
layers thought to
generate N1
III
IV
V
Axonal
neuro-
Axonal
neuroVI
filaments
Cell
bodies
filaments
(Ponton, Moore &
Eggermont 1999)
Cell
bodies
NAL: Dillon, Van Dun, Carter, Gardner-Berry
Latency versus age
Function = 271-106*log10(12*X) -7.8*(log10(12*X))^2+6.94*(log10(12*X))^3
300
280
NAL data
260
Sharma et al
240
Latency of P1 (ms)
220
200
180
160
140
120
100
80
60
40
20
0.1
0.2
0.5
1
2
Age (y ears)
5
10
20
50
NAL: Dillon, Van Dun, Carter, Gardner-Berry
MEASURING
CORTICAL
RESPONSES
NAL: Dillon, Van Dun, Carter, Gardner-Berry
Practical demonstration (by video):
speech sounds and infants
Set-up – equipment diagram
Video of infant being tested
NAL: Dillon, Van Dun, Carter, Gardner-Berry
Practical implementation of
cortical testing: HearLab
Disclosure: NAL will get a royalty for each unit sold.
Thank you: The HearLab development team –
Teck Loi, Barry Clinch, Isabella Tan, Ben Rudzyn,
Lyndal Carter, Dan Zhou, Scott Brewer
NAL: Dillon, Van Dun, Carter, Gardner-Berry
NAL: Dillon, Van Dun, Carter, Gardner-Berry
Equipment configuration
NAL: Dillon, Van Dun, Carter, Gardner-Berry
CAEP room set-up at the
National Acoustic Laboratories
Free Field
Speaker
Baby sits on parent’s
lap in the centre of the
room or in a high chair.
NAL: Dillon, Van Dun, Carter, Gardner-Berry
Electrode equipment
NAL: Dillon, Van Dun, Carter, Gardner-Berry
Videos
Attaching electrodes 01:00 2.30  end
Headband usage
Putting in hearing aids
Keeping alert carousel
NAL: Dillon, Van Dun, Carter, Gardner-Berry
NAL: Dillon, Van Dun, Carter, Gardner-Berry
Keeping electrodes on the baby
using a headband
NAL: Dillon, Van Dun, Carter, Gardner-Berry
Keeping the baby awake!
NAL: Dillon, Van Dun, Carter, Gardner-Berry
Tools for keeping baby quiet, alert, awake
NAL: Dillon, Van Dun, Carter, Gardner-Berry
(More) tools for keeping baby quiet, alert, awake
NAL: Dillon, Van Dun, Carter, Gardner-Berry
(Yet more) tools for keeping baby quiet, alert, awake
NAL: Dillon, Van Dun, Carter, Gardner-Berry
Practical issues in measurement
Averaging
Electrode location
Artefact rejection
Filtering
Number of runs
Head support
Interference – lighting, mobile phones, active electrodes
NAL: Dillon, Van Dun, Carter, Gardner-Berry
Averaging
NAL: Dillon, Van Dun, Carter, Gardner-Berry
Electrode location
Non-inverting
+
Inverting
Ground
NAL: Dillon, Van Dun, Carter, Gardner-Berry
Artefact rejection
Peak voltage > 150 µV
Rms voltage
Insufficient voltage
NAL: Dillon, Van Dun, Carter, Gardner-Berry
Filtering
NAL: Dillon, Van Dun, Carter, Gardner-Berry
Head support
Yes!!
NAL: Dillon, Van Dun, Carter, Gardner-Berry
Reducing measurement variability
(random electrical signals)
 Speeding up measurements
 Increasing validity of interpretation
NAL: Dillon, Van Dun, Carter, Gardner-Berry
Active electrodes
NAL: Dillon, Van Dun, Carter, Gardner-Berry
Capacitive Coupling 50 Hz
Passive Electrodes
NAL: Dillon, Van Dun, Carter, Gardner-Berry
Capacitive Coupling 50 Hz
Active Electrodes
NAL: Dillon, Van Dun, Carter, Gardner-Berry
Capacitive Coupling 50 Hz
Passive Electrodes
Active Electrodes
NAL: Dillon, Van Dun, Carter, Gardner-Berry
Conclusions: Active on-scalp preamplification
Electrical leads are less sensitive to:
• capacitive coupling electrical interference
(because of low amplifier output impedance)
• Inductive coupling electrical interference
(because of gain within pre-amplifier)
NAL: Dillon, Van Dun, Carter, Gardner-Berry
Signal processing options
• Noise down by x 
measurement time down by x2
• Several potential improvements
under research
NAL: Dillon, Van Dun, Carter, Gardner-Berry
RESEARCH RESULTS
WITH CORTICAL
RESPONSES
NAL: Dillon, Van Dun, Carter, Gardner-Berry
Impact of auditory experience on
cortical responses
NAL: Dillon, Van Dun, Carter, Gardner-Berry
Children with CI (Sharma,2002) and NAL aided hearing impaired
infants/children (N=40) using speech stimuli presented at 65 dB SPL.
NAL Aided hearing impaired
Infants and children (not all have P1)
NAL: Dillon, Van Dun, Carter, Gardner-Berry
Maturation
with time
“in sound”
Ponton and
Eggermont 2007
NAL: Dillon, Van Dun, Carter, Gardner-Berry
Conclusion: Auditory system maturity
• The latency of cortical potentials indicate
the maturity of the auditory system.
• Latency matures consistent with the time
“in sound”; (Ponton and Eggermont, 2007)
• …. provided implantation occurs by 3.5
years of age (Sharma, 2002)
NAL: Dillon, Van Dun, Carter, Gardner-Berry
Cortical responses to different
sounds
NAL: Dillon, Van Dun, Carter, Gardner-Berry
A
d
u
ltsa
m
p
litu
d
eN
1
N1, P2
amplitude
0
.5
1
.0
1
.5
2
.0
• N1, P2
amplitude
advantage at
Cz in adults for
all stimuli
Amplitude(microvolts)
2
.5
3
.0
3
.5
+
/S
E
C
3
C
z
C
4
4
.0
4
.5
5
.0
5
0
0
H
z
1
k
H
z
2
k
H
z
4
k
H
z
d
a
e
g
a
e
k
a
e
ta
e
S
tim
u
lu
s
A
d
u
ltsa
m
p
litu
d
eP
2
3
.6
3
.2
2
.8
2
.4
Amplitude(microvolts)
2
.0
1
.6
+
/-S
E
C
3
C
z
C
4
1
.2
0
.8
0
.4
NAL: Dillon, Van Dun, Carter, Gardner-Berry
5
0
0
H
z
1
k
H
z
2
k
H
z
4
k
H
z
d
a
e
S
tim
u
lu
s
g
a
e
k
a
e
ta
e
Voltage
Multivariate Analysis of Variance
• Divide each record into 50 ms time bins
Time
• Average data points within each time bin
• Use these averages as variables in MANOVA analysis
• MANOVA finds the combination of variables that best distinguishes
two or more stimuli
• Result is probability of two stimuli coming from different distributions
NAL: Dillon, Van Dun, Carter, Gardner-Berry
Number of subjects
Number of infants (N=20) with significantly different
cortical responses to pairs of stimuli
20
15
10
5
0
m vs
m vs
vs gae
g
mae
vs ttae mae
vs gae
g
taet vs
500 vs 2000
Based on MANOVA at Cz, 101 to 500 ms post-onset, in eight bins each 50 ms
NAL: Dillon, Van Dun, Carter, Gardner-Berry
Are /tae/ & /mae/ cortical responses
different in hearing impaired children?
• 10 subjects (5 with
poor hearing aid
progress), 14 ears
• 8 infants 6-20 months,
2 children 4 & 10 years
• 4 moderate, 8 severe,
2 profound ears
• 64% had different
responses based on
individual ANOVA
• 9 subjects, 9 ears
• 6-12 years
• sloping, mild-severe
hearing loss
• hearing aids fitted to
NAL-NL1 but not
optimally
• 55% had different
responses
NAL: Dillon, Van Dun, Carter, Gardner-Berry
Grand Average n = 16 infants
+
MM
OO
OR
UU
EE
AH
SH
SS
-
0.00
400.00
200.00
ms
600.00
NAL: Dillon, Van Dun, Carter, Gardner-Berry
Number of subjects (out of 20) with
significant differences between responses
ah
ah
ee
mm
oo
or
sh
ss
uu
ee mm
7
7
oo
or
sh
ss
uu
4
7
7
12
12
13
6
8
11
12
10
9
8
8
10
10
7
7
13
10
13
12
10
7
3
14
4
6
7
8
8
7
11
8
7
12
12
10
13
12
12
10
10
10
10
3
13
9
7
13
7
14
11
11
NAL: Dillon, Van Dun, Carter, Gardner-Berry
+
P2
1.25µV
Adults
P1
---
N1
-100
+
0
100
200
300
400
500
/tae/
/gae/
/mae/
500 Hz
2 kHz
Time (ms)
P
5µV
--
Infants
-100
0
100
200
300
Time (ms)
400
500
NAL: Dillon, Van Dun, Carter, Gardner-Berry
Conclusion: Cortical response
shape for different speech sounds
• Cortical response shape for different
speech sounds, and tone bursts are similar,
but not identical, in shape across stimuli.
Cortical responses to sounds presented in
isolation are better suited as indicators of
detection.
Future work: Cortical response to
change, as a measure of discrimination
NAL: Dillon, Van Dun, Carter, Gardner-Berry
Amplitude
Amplitude
Amplitude
G
1
0
-1
0
Three speech sounds:
5
10
15
Time (ms)
M
20
25
30
/m/ /g/ /t/
1
0
-1
0
5
10
15
Time (ms)
T
20
25
30
5
10
15
Time (ms)
20
25
30
1
0
-1
0
70.0
1/3 octave SPL
60.0
50.0
40.0
30.0
20.0
10.0
0.0
-10.0
-20.0
100
NAL: Dillon, Van Dun, Carter, Gardner-Berry
GAE
TAE
MAE
ILTASS @ 65
1000
Frequency
10000
Automatic detection of cortical
responses
NAL: Dillon, Van Dun, Carter, Gardner-Berry
Why not obligatory cortical responses?
•
•
•
•
variable shape across ages
variable shape with auditory experience
variable shape from person to person
variable shape from time to time (state of person,
especially sleepiness)
• variable shape with stimulus
• Variable shape with inter-stimulus interval
high skill level needed to read responses
NAL: Dillon, Van Dun, Carter, Gardner-Berry
Desirable characteristics
• No reliance on a template
• Able to use information from
contributing portions of waveform
• Able to discount non-contributing
portions of waveform
Hotellings T2
NAL: Dillon, Van Dun, Carter, Gardner-Berry
Voltage
Analysis using Hotellings t2 statistic
X3
Time
•
•
•
•
Divide each record into 50 ms time bins
Average data points within each time bin
Use these averages as variables in Hotellings t2 analysis
Result is probability of the waveform being random noise
X = a1X1 + a2X2 + ........ + a9X9
Test: is there any set of weighting coefficients for which X ≠ 0?
NAL: Dillon, Van Dun, Carter, Gardner-Berry
Presentation of
average
response in
series
NAL: Dillon, Van Dun, Carter, Gardner-Berry
Probability Sensitivity
(response|stimulus)
Receiver Operating Characteristics –
Expert judges
In-series - 60 presentations
-10 dB
1.00
-10 dB
0.80
0 dB
0.60
0 dB
0.40
10 dB
0.20
10 dB
0.00
20 dB
0.00
0.20
0.40
0.60
0.80
Probability (response|no stimulus)
NAL: Dillon, Van Dun, Carter, Gardner-Berry
1 - Specificity
1.00
20 dB
30 dB
30 dB
ROC – 200 repetitions;
adults with normal hearing to moderate loss
1.0
10 dB
0.9
0 dB
0.8
Power
0.7
0.6
- 10 dB
0.5
0.4
0.3
0.2
0.1
0.0
0.0
0.2
0.4
0.6
0.8
1.0
Type I error
NAL: Dillon, Van Dun, Carter, Gardner-Berry
d’ results - for 200 stimuli
4
3
d'
2
1
Hotellings
Experts - series
Experts- isolation
0
-1
-10
0
10
20
30
Sensation level (dB)
NAL: Dillon, Van Dun, Carter, Gardner-Berry
d’ results - for 60 stimuli
For hit rate of 80% and false
alarm rate of 5%,
d’=2.5
4
3
d'
2
1
Hotellings
Experts - series
Experts- isolation
0
-1
-10
0
10
20
30
Sensation level (dB)
NAL: Dillon, Van Dun, Carter, Gardner-Berry
Infants: Hotellings versus experts
Normal hearing infants aged 7 to 16 months
5.0
4.5
4.0
3.5
3.0
d'
2.5
Examiners (InSeries)
2.0
Hotelling's T2
1.5
1.0
0.5
0.0
-0.5
-1.0
0
10
20
30
40
Sensation level
NAL: Dillon, Van Dun, Carter, Gardner-Berry
Effect of sensation level, hearing
loss, and unrelated EEG or muscle
noise
NAL: Dillon, Van Dun, Carter, Gardner-Berry
Growth of amplitude with SL
adults; tonal stimuli
7
6
5
4
3
2
N1 to P2 amplitude (uV
1
0
Normal hearing
Hearing impaired
-1
10
20
30
Sensation level (dB)
NAL: Dillon, Van Dun, Carter, Gardner-Berry
Loudness growth above threshold
Hellman &
Meiselman,
1990
NAL: Dillon, Van Dun, Carter, Gardner-Berry
Effect of response amplitude on
detectability
z-level A = -0.5956-0.6753*x
4
100 epochs
2
Adults, tonal
Normal hearing
Hearing loss
10, 20, 30 dB SL
z score
0
-2
P<0.05
-4
-6
-8
-10
-6
-4
-2
0
2
4
6
8
N1 to P2 amplitude (uV)
10
12
14
NAL: Dillon, Van Dun, Carter, Gardner-Berry
Detectability (adults; tonal stimuli)
0
0
Normal hearing
Hearing impaired
-1
-1
P=0.05
-2
-2
P=0.01
-3
-3
P=0.001
z score
-4
-4
-5
-5
-6
-6
10
20
Sensation level (dB)
30
NAL: Dillon, Van Dun, Carter, Gardner-Berry
Significant responses – normal hearing and hearing impaired
Adults; tonal stimuli (n=100 or 200)
1000 Hz
Prop. of responses with
detection p < 0.05
1.0
0.9
Normal hearing
0.8
0.7
Hearing Impaired
0.6
0.5
0.4
0.3
0.2
0.1
0.0
0
10
20
30
Sensation level
NAL: Dillon, Van Dun, Carter, Gardner-Berry
Matlab z vs Behavioural SL
2
43
30
2
0
P=0.05
0. 1
-2
0.01
0.001
0.0001
z
-4
-6
-8
-10
-12
-30
0.00001
G FL
G HB
G LB
2
M FL
M HB
M LB
T FL
T HB
T LB
-20
0.0000001
0.000000001
39
-10
0
10
SL (dB)
145
20
30
40
NAL: Dillon, Van Dun, Carter, Gardner-Berry
Proportion with responses present adults
1000 Hz
1.0
0.9
0.8
0.7
0.6
0.5
0.4
0.3
0.2
0.1
0.0
Normal hearing
Hearing Impaired
0
Prop. of responses with
detection p < 0.05
Prop. of responses with
detection p < 0.05
500 Hz
10
20
1.0
0.9
0.8
0.7
0.6
0.5
0.4
0.3
0.2
0.1
0.0
Normal hearing
Hearing Impaired
0
30
10
20
4000 Hz
Normal hearing
Hearing Impaired
0
Prop. Responses with
detection p < 0.05
Prop. responses with detection
p < 0.05
2000 Hz
1.0
0.9
0.8
0.7
0.6
0.5
0.4
0.3
0.2
0.1
0.0
10
20
Sensation level
30
Sensation level
Sensation level
30
1.0
0.9
0.8
0.7
0.6
0.5
0.4
0.3
0.2
0.1
0.0
Normal hearing
Hearing Impaired
0
10
20
30
Sensation level
NAL: Dillon, Van Dun, Carter, Gardner-Berry
…….. but infants move around !
NAL: Dillon, Van Dun, Carter, Gardner-Berry
Residual noise level
rms noise = standard deviation / √n
NAL: Dillon, Van Dun, Carter, Gardner-Berry
Residual noise levels (for 100 epochs)
100
90
80
70
Awake
adults
No of obs
60
50
40
30
20
10
0
0
0.6
1.0
0.8
1.4
1.2
1.8
1.6
2.2
2.0
2.6
5
2.4
Residual noise level (uV)
30
28
26
24
22
20
No of obs
18
16
Awake
infants
But also
larger
responses
14
12
10
8
6
4
2
0
2.2
2.6
2.4
3.0
2.8
Res idual nois e lev el
3.4
3.2
3.8
3.6
4.2
4.0
4.6
4.4
4.8
NAL: Dillon, Van Dun, Carter, Gardner-Berry
Growth of amplitude with SL
18
16
14
12
10
8
Hearing impaired adults
6
N1 to P2 amplitude (uV
4
2
0
10
20
30
Sensation level (dB)
NAL: Dillon, Van Dun, Carter, Gardner-Berry
Detectability versus residual noise
- infants Include condition: "SL"=30
3
2
0
-1
-2
P=0.05
z-level
More detectable
1
-3
-4
-5
-6
2.8
3.0
3.2
3.4
3.6
3.8
4.0
4.2
Residual noise level
NAL: Dillon, Van Dun, Carter, Gardner-Berry
Proportion with responses present (p<0.05)
– normal hearing infants; 100 epochs
90%
80%
70%
60%
50%
40%
30%
20%
10%
0%
Noise <3.4 uV
Noise >3.4 uV
10
20
30
Sensation level (dB)
NAL: Dillon, Van Dun, Carter, Gardner-Berry
Detection of speech sounds
-20
-10
-5
0
5
10
15
20
25
30
35
40
0.05
U1m
U1g
U2g
U2t
U3m
U3t
U4m
U4g
U5g
U5t
U6m
U6t
A1m
A2g
A2t
A4m
A4g
A5g
A5t
A6m
A6t
A7m
A7g
A8g
A8t
A9m
A9t
A10m
A10g
A11g
A11t
A12m
A12t
A13m
A13g
A14g
A14t
A15m
A15t
A17g
A17t
A18m
A18t
1
Probability ofa true response
0.1
0.01
0.001
0.0001
Sesnation level (dB)
NAL: Dillon, Van Dun, Carter, Gardner-Berry
Conclusions: Detecting cortical
response presence
• Large responses are more easily detected
• Response amplitude grows with sensation level
• Response amplitude at low SL is larger for
people with sensorineural hearing loss that for
people with normal hearing
• Responses are more easily detected when
residual noise is low (<3.4 µV for infants; < 1.5
µV for adults)
NAL: Dillon, Van Dun, Carter, Gardner-Berry
Cortical responses and
functional performance
Do cortical responses tell us about
real-life auditory performance?
NAL: Dillon, Van Dun, Carter, Gardner-Berry
Parent’s Evaluation of Aural/oral performance in
Children (PEACH) Questionnaire
• Parents are asked to describe their baby’s
aural/oral skills based on real-life experiences
(listening in quiet and in noise and alertness to
environmental sound)
• Scores are assigned based on the number of
observed behaviors and how frequently these
occur.
• Final overall score of 0 – 40 can be calculated
(and reported as a percentage).
NAL: Dillon, Van Dun, Carter, Gardner-Berry
Results: PEACH score by age
Normative data
curve
NAL: Dillon, Van Dun, Carter, Gardner-Berry
Functional deficit vs number of
cortical responses present at
Functional deficit
0
-10
0
1
2
3
N = 24; p = 0.001
12 sensorineural
-20
7 auditory
neuropathy
-30
5 multiply disabled
-40
-50
Number of corticals present
NAL: Dillon, Van Dun, Carter, Gardner-Berry
Functional deficit versus cortical score
* All aided children
rs =0.60; n=24; p = 0.001
* SN only
rs=0.61; n=12; p = 0.02
* MD only
rs=0.82, n=5; p = 0.04
* AN only
rs=0.36; N=7; p = 0.22
NAL: Dillon, Van Dun, Carter, Gardner-Berry
Conclusions: Cortical responses and
functional performance
• The greater the number of speech
sounds that result in cortical
responses in aided infants, the
greater the functional performance
in real life, on average
NAL: Dillon, Van Dun, Carter, Gardner-Berry
CLINICAL APPLICATIONS
NAL: Dillon, Van Dun, Carter, Gardner-Berry
Estimating hearing thresholds in
non-responsive adults
Elderly infirm – stroke, dementia
Workers’ compensation
NAL: Dillon, Van Dun, Carter, Gardner-Berry
Practical demonstration
pure tones and adults
Set-up – equipment diagram
Screen sequence
Electrode attaching
Actual test – insert phones, pure tones.
NAL: Dillon, Van Dun, Carter, Gardner-Berry
Good agreement between CAEP and
audiometric thresholds in awake adults
Tsui, Wong & Wong 2002
NAL: Dillon, Van Dun, Carter, Gardner-Berry
From: Rickards, F. et al (1996) Cortical Evoked Response Audiometry in
noise induced hearing loss claims. Aust. J. Otol. 2 (3)
NAL: Dillon, Van Dun, Carter, Gardner-Berry
Test sequence
Evaluation using HearLab
• Automated response
detection
60
Response
present
P < 0.05
• 40 ms tone bursts
Response
absent
P > 0.05
85
30
15
45
5
0
25
10
20
40
35
100
75
55
50
70
65
80
110
95
90
105
NAL: Dillon, Van Dun, Carter, Gardner-Berry
Cortical threshold vs behavioural
threshold - adults
120
100
80
60
40
Cortical threshold (dB HL
20
r2 = 0.77; r = 0.88, p < 0.0001; y = 9.7 + 0.914*x
0
0
20
40
60
80
Behavioral threshold (dB HL)
100
120
NAL: Dillon, Van Dun, Carter, Gardner-Berry
Cortical thresholds minus Behavioral thresholds
68%
+5 dB
84%
+10 dB
91%
+15 dB
NAL: Dillon, Van Dun, Carter, Gardner-Berry
Histogram (difference_toneburst-puretone.sta 6v*68c)
70
60
50
40
No of obs
30
20
10
500
1000
2000
4000
0
-16 -14 -12 -10
-8
-6
-4
-2
0
2
4
6
8
10
12
14
16
NAL: Dillon, Van Dun, Carter, Gardner-Berry
Davis (1965) Cortical evoked potential
versus behavioural thresholds
NAL: Dillon, Van Dun, Carter, Gardner-Berry
Conclusions: Estimating behavioural
thresholds in hearing-impaired adults
• Cortical thresholds overestimate behavioural
thresholds by 2.4 dB, on average
• Standard deviation of cortical – behavioural
threshold differences is 6.3 dB
• Applications: hearing compensation, clients
unable to respond
NAL: Dillon, Van Dun, Carter, Gardner-Berry
Cortical potentials to assess
speech audibility for infants
NAL: Dillon, Van Dun, Carter, Gardner-Berry
Clinical implications of corticals
Significant
response is
obtained to
speech at 65
dB SPL
No significant
response is
obtained to
speech at 65
dB SPL or to
speech at 75
dB SPL
Morphology
normal for age
All is well
Morphology
abnormal for
age
Repeat test
Low residual
noise
Re-check fitting;
Consider all options
High residual
noise
Draw no conclusion !
NAL: Dillon, Van Dun, Carter, Gardner-Berry
Noisy results - chewing
NAL: Dillon, Van Dun, Carter, Gardner-Berry
Clinical implications of corticals (cont)
Mixed results
(and noise is
low)
Mixed results
(and noise is
high)
No /t/
response
Review HF gain
or loss estimate
No /g/
response
Review mid-freq
gain or loss
estimate
No /m/
response
Review LF gain or loss
estimate
Draw no conclusions from
missing response !
NAL: Dillon, Van Dun, Carter, Gardner-Berry
Hearing loss at birth ….. for parents
Parental
denial
Unaided
testing at
conversational
levels
Working
towards a
solution
Aided
testing at
conversational
levels
Pessimism
and
hopelessness
NAL: Dillon, Van Dun, Carter, Gardner-Berry
Some recent cases
Hsiuwen Chang
NAL: Dillon, Van Dun, Carter, Gardner-Berry
No /m/ response
NAL: Dillon, Van Dun, Carter, Gardner-Berry
Case 1
No cortical responses, and the
results helped the parents accept
the need for cochlear implants
• Age at aided cortical testing
– Visit 1
6 weeks old (Initial hearing aid fitting day)
– Visit 2
3 months old
NAL: Dillon, Van Dun, Carter, Gardner-Berry
Tone-burst ABR (Estimated levels in dB nHL)
500 Hz
1000 Hz
2000 Hz
4000 Hz
Right
>95
>95
>95
>95
Left
>95
>95
>95
>95
Estimated Audiogram (dB HL) at Visit 1
500 Hz
1000 Hz
2000 Hz
4000 Hz
Right
85
90
95
95
Left
85
90
95
95
Estimated Audiogram (dB HL) at Visit 2
500 Hz
1000 Hz
2000 Hz
4000 Hz
Right
90
100
105
105
Left
90
100
105
105
NAL: Dillon, Van Dun, Carter, Gardner-Berry
Visit 1
P < 0.05 ?
…. No
Increase gain at all
frequencies
NAL: Dillon, Van Dun, Carter, Gardner-Berry
Visit 2
NAL: Dillon, Van Dun, Carter, Gardner-Berry
• The infant received bilateral cochlear
implantations at 5 months of age.
• Email from the baby’s parents ~
“Thank you so much for the information
you gave us on the previous testing as it
helped us with our decision to proceed
with the implants.”
NAL: Dillon, Van Dun, Carter, Gardner-Berry
Case 2
No cortical responses, even after hearing
aids have been increased in gain for the
third time and the parents don’t want a
cochlear implant for their baby
• Age at aided cortical testing
– Visit 1
13 weeks old
– Visit 2
17 weeks old
– Visit 3
21 weeks old
• Hearing aid fitting at 8 weeks of age
NAL: Dillon, Van Dun, Carter, Gardner-Berry
Estimated Audiogram (dB HL) at Visit 1
500 Hz
1000 Hz
2000 Hz
4000 Hz
Right
90
80
80
85
Left
85
75
75
95
Estimated Audiogram (dB HL) at Visit 2
500 Hz
1000 Hz
2000 Hz
4000 Hz
Right
100
90
90
95
Left
95
85
85
95
Estimated Audiogram (dB HL) at Visit 3
500 Hz
1000 Hz
2000 Hz
4000 Hz
Right
100
100
100
100
Left
100
100
100
100
NAL: Dillon, Van Dun, Carter, Gardner-Berry
Visit 1
Increase gain at all
frequencies
NAL: Dillon, Van Dun, Carter, Gardner-Berry
Visit 2
Left aided
Right aided
Increase gain at all
frequencies
NAL: Dillon, Van Dun, Carter, Gardner-Berry
Visit 3
NAL: Dillon, Van Dun, Carter, Gardner-Berry
• The parents still believe that their baby
boy can be oral by using hearing aids.
• They are hoping to see that their baby
can benefit from more powerful hearing
aids.
• The baby’s hearing aids were changed
from Siemens Explorer 500 P to Phonak
Una SP after Visit 3.
NAL: Dillon, Van Dun, Carter, Gardner-Berry
Case 3
Corticals provided reassurance
about the baby hearing well
• Age at aided cortical testing
– Visit 1
4.5 months old
– Visit 2
5.5 months old
• Hearing aid fitting at 5 weeks of age
NAL: Dillon, Van Dun, Carter, Gardner-Berry
Tone-burst ABR (Estimated levels in dB nHL)
500 Hz
1000 Hz
2000 Hz
4000 Hz
Right
40
DNT
60
70
Left
40
DNT
70
80
Estimated Audiogram (dB HL) at Visit 1
500 Hz
1000 Hz
2000 Hz
4000 Hz
Right
30
40
55
65
Left
30
45
65
75
Estimated Audiogram (dB HL) at Visit 2
500 Hz
1000 Hz
2000 Hz
4000 Hz
Right
40
45
55
65
Left
40
50
65
75
NAL: Dillon, Van Dun, Carter, Gardner-Berry
Visit 1
Increase low- and midfrequency gain
NAL: Dillon, Van Dun, Carter, Gardner-Berry
Visit 2
NAL: Dillon, Van Dun, Carter, Gardner-Berry
Email from mother:
“We feel very relieved, as our faith has been
restored in the hearing aids as a result of
what we discovered from the results.”
NAL: Dillon, Van Dun, Carter, Gardner-Berry
Case 4
Too few significant cortical
responses, and the aid gain was
increased, resulting in more
cortical responses
• Age at aided cortical testing
– Visit 1
8 months old
– Visit 2
9 months old
• Hearing aids have been increased in gain
two weeks before the second visit.
• Hearing aid fitting at 9 weeks of age
NAL: Dillon, Van Dun, Carter, Gardner-Berry
Estimated Audiogram (dB HL) at Visit 1
500 Hz
1000 Hz
2000 Hz
4000 Hz
Right
45
50
55
55
Left
45
55
65
55
Estimated Audiogram (dB HL) at Visit 2
500 Hz
1000 Hz
2000 Hz
4000 Hz
Right
55
50
55
55
Left
55
55
65
55
NAL: Dillon, Van Dun, Carter, Gardner-Berry
Visit 1
Visit 2
NAL: Dillon, Van Dun, Carter, Gardner-Berry
Case 5
A case where cortical testing
was not possible
• Age at testing: 4.5 years
• Multiple disabilities
• A reliable behavioural audiogram
has not yet been obtained.
NAL: Dillon, Van Dun, Carter, Gardner-Berry
• She was wiggling all the time.
This is the quietest state she could be, but
only lasted for a few seconds.
NAL: Dillon, Van Dun, Carter, Gardner-Berry
A case where the unaided /m/
was present but the aided /m/
was absent.
• Cortical testing at 8 months of age, nine
days after the initial hearing aid fitting
NAL: Dillon, Van Dun, Carter, Gardner-Berry
Estimated Audiogram
500 Hz
1000 Hz
2000 Hz
4000 Hz
Right
40
35
40
45
Left
40
35
40
45
NAL: Dillon, Van Dun, Carter, Gardner-Berry
Unaided
Aided
NAL: Dillon, Van Dun, Carter, Gardner-Berry
Hearing Aid Coupler Gain at 65 dB SPL Input
250 Hz
500 Hz
1000 Hz
2000 Hz
4000 Hz
<0
0
7
15
20
* Both hearing aids are set the same.
NAL: Dillon, Van Dun, Carter, Gardner-Berry
Application for auditory neuropathy spectrum
disorder (AN)
• 20% of babies found to have hearing loss
at birth in NSW have AN
• Management unclear (no device, FM
system, hearing aid or cochlear implant)
• Rance showed close relationship between
cortical response in older children and
benefit from hearing aids
• ABR not indicative of behavioural
thresholds
NAL: Dillon, Van Dun, Carter, Gardner-Berry
Problem
1. In babies with ANSD we can’t predict the
audiogram like we can for a baby with a
typical sensory hearing loss.
2. We can’t predict speech discrimination
ability.
What approach to
amplification & early
intervention do we
recommend?
creating sound valueTM
NAL: Dillon, Van Dun, Carter, Gardner-Berry
State-wide Infant Screening of Hearing (SWIS-H)
Population based Universal newborn hearing screening program in NSW,
Australia
(AABR used for both well babies & NICU babies)
BabiesProportion
diagnosed with
a bilateral,
moderate or
of babies
diagnosed
greater hearing loss.
through UNHS with AN/AD
14%
6%
80%
AN/AD with risk factors
AN/AD no risk factors
Sensory/Permanent
conductive
Sensory
Hg Loss
L. Murphy. Presented at the International Newborn Hearing Screening conference, Lake Como, Italy 2006
NAL: Dillon, Van Dun, Carter, Gardner-Berry
Problem 1: How can we work out the degree of the
hearing loss when there is no ABR waveform?
•
•
When we diagnose a young baby
with a hearing loss we use Auditory
Brainstem Response (ABR) testing
and track wave V down to
threshold.
The wave V thresholds across
different frequencies can then be
used to predict an audiogram.
FREQUENCY (Hz)
500
1k
2k
4k
8k
0
10
20
30
40
50
60
70
80
90
100
110
NAL: Dillon, Van Dun, Carter, Gardner-Berry
Problem 2: How do we work out what a baby’s speech
500
1000ability
2000 is
4000
discrimination
like? FREQUENCY (Hz)
Child B
Child A
500
1000
2000
4000
500
0
0
10
10
20
20
30
30
40
40
50
50
60
60
70
70
80
80
90
90
100
100
110
110
Speech discrimination
score = 87%
1000
2000
4000
Speech discrimination
score = 32%
NAL: Dillon, Van Dun, Carter, Gardner-Berry
What do we recommend to parents when
we’re walking in blind!
NAL: Dillon, Van Dun, Carter, Gardner-Berry
Aims & Measures:
1.
Predict whether average
hearing levels are:
•
•
<80 dBHL
(hearing aid range)
>80 dBHL
(cochlear implant range)
2. Predict whether auditory
function is significantly
affected
(with the view to look at speech
discrimination ability in the
future)
1. Cortical Auditory Evoked Potentials
a) Presence/absence of cortical response to different frequency stimuli.
2. Functional auditory ability:
a) IT-MAIS and/or
b) PEACH
NAL: Dillon, Van Dun, Carter, Gardner-Berry
Congenital ANSD & Degree of hearing loss
Total No.= 62 ears
Profound:
(NAL ANSD population –
multiple studies)
Cochlear Implants
(16 ears):
•2 unilateral CI
• 4 bilateral.
0%
25%
10%
Hard
Easy!
Mild:
• No CIs at present
Nothing to lose
Easy!
Less to lose
Normal/Borderline
Mild
Moderate
Severe
Profound
Hard
44%
Severe:
21%
Cochlear Implants (13 ears)
Moderate:
• 6 proceeded with a unilateral CI.
• 1 proceeded with
a unilateral CI.
creating sound valueTM
NAL: Dillon, Van Dun, Carter, Gardner-Berry
Q 1. Are speech sounds audible?
Group 1
4FA <80 dBHL = 7 subjects
Scenario 1
Unaided CAEPs
present.
Group 2
4FA >80 dBHL = 8 subjects
Scenario 2
Scenario 3
Unaided CAEPs
absent.
Unaided CAEPs
absent.
Aided CAEPs
present.
Aided CAEPs
absent.
Hearing likely to be
normal-mild.
Hearing loss likely
to be moderatesevere.
creating sound valueTM
Hearing loss more likely
to be profound.
NAL: Dillon, Van Dun, Carter, Gardner-Berry
Q 2. Are there signs that auditory functional
ability might be affected?
Rance et al, 2002, Ear & Hearing Vol. 23(3)
Score >30%
Score <30%
creating sound valueTM
NAL: Dillon, Van Dun, Carter, Gardner-Berry
CAEP result assumptions
Speech sounds used for CAEP testing need to
be at a high enough level above threshold (i.e.
sensation level) to elicit a response.
• Assumed audibility needed
to be >=25 dBHL for each
stimulus to elicit a response
(audibility calculator).
• Assumed PTA thresholds
be
didn’t change significantly Should
audible
between CAEP testing &
the acquisition of reliable
PTA results.
Expect
CAEP
• Keep in mind: Functional
assessments weren’t
always performed close to
the time of CAEP testing.
creating sound valueTM
Less
audible
Less
likely to
see CAEP
Inaudible
Don’t
expect
CAEP
NAL: Dillon, Van Dun, Carter, Gardner-Berry
Presence/Absence CAEPs
< 80dBHL
n= 7 subjects in group (12 ears)
n= 36 responses to analyze (m, g, t)
2 subjects subsequently
found to be under-fitted for
at least 2/3 responses.
CAEPs were absent for at least
2/3 stimuli so CAEPs guided
appropriate recommendation to
review fitting & management.
1 abnormal PEACH
1 inconsistent functional audibility
results (normal PEACH at 7 mths but
abnormal IT-MAIS at 13 mths)
5 subjects
Should have had reasonable audibility so CAEP
responses were expected for at least 2/3 stimuli bilaterally.
Present
(for at least 2/3
responses bilaterally)
3 subjects
Will these ones demonstrate
good speech discrimination
long term?
1 normal PEACH
1 no concerns regarding auditory behavior
1 unknown.
creating sound valueTM
Absent
(for at least 2/3
responses bilaterally)
2 subjects
Will these ones
demonstrate poor speech
discrimination long term?
1 abnormal PEACH at 2 years
& 1 normal PEACH at 12 mths
but under review
NAL: Dillon, Van Dun, Carter, Gardner-Berry
Presence/Absence CAEPs
> 80dBHL
n= 7 subjects in group (12 ears)
n= 36 responses to analyze (m, g, t)
6 subjects subsequently found to
have poor audibility (even high gain
hearing aids wouldn’t have been
sufficient due to severity of loss)
CAEPs were absent for all stimuli
tested bilaterally so CAEPs prompted
appropriate recommendation to
review fitting & management.
5 abnormal PEACH or IT-MAIS
1 inconsistent functional audibility
results (normal PEACH at 7 mths but
abnormal IT-MAIS at 13 mths. One
ear <80 one ear >80 dBHL)
creating sound valueTM
1 subjects (only 1 ear)
Should have had reasonable audibility so CAEP responses
were expected for at least 2/3 stimuli in one ear.
Present
(for at least 2/3
responses bilaterally)
0 subjects
Absent
(for at least 2/3
responses bilaterally)
1 subjects
Will this baby demonstrate
poor speech
discrimination long term?
CAEPs prompted
appropriate
recommendation to
review fitting &
management.
Abnormal PEACH at
20 months
NAL: Dillon, Van Dun, Carter, Gardner-Berry
Auditory Neuropathy case
study
creating sound valueTM
NAL: Dillon, Van Dun, Carter, Gardner-Berry
Electrocochleography - ECochG
A ‘Golf Club’ electrode is placed in the round
window niche of the cochlear.
creating sound valueTM
NAL: Dillon, Van Dun, Carter, Gardner-Berry
ECochG in ANSD cases
ANSD
Abnormal Positive Potentials
Normal Hearing
Lt 4kHz ECochG
90dB
Left 8 kHz ECochG
ECochG 90dB 1
10ms 20µV 90 dBnHL
14
110 dBnHL
80dB
ECochG 80dB 2
10ms 20µV 80 dBnHL
73
70dB
ECochG 70dB 3
100 dBnHL
10ms 10µV 70 dBnHL
89
60dB
ECochG 60dB 4
90 dBnHL
10ms 10µV 60 dBnHL
86
50dB
ECochG 50dB 5
10ms 5µV50 dBnHL
128
ECochG 40dB 6
80 dBnHL
40dB
30dB
70 dBnHL
10ms 2µV30 dBnHL
128
ECochG 20dB 8
60 dBnHL
10ms 5µV40 dBnHL
128
ECochG 30dB 7
20dB
10ms 1µV20 dBnHL
128
Normal responses can be seen
right down to soft levels.
creating sound valueTM
An unusual positively shaped peak is
seen at high & moderate intensities.
NAL: Dillon, Van Dun, Carter, Gardner-Berry
FREQUENCY (Hz)
250
500
750
1000
1500
2000
3000
4000
6000
8000
ABR
28/8/03 - NR
0
10
20
30
40
50
60
70
80
ABR
(CM only)
90
100
ABR
(CM only)
110
Case Study 2
WP ASA 2004
NAL: Dillon, Van Dun, Carter, Gardner-Berry
FREQUENCY (Hz)
250
500
750
1000
1500
2000
3000
4000
6000
8000
ABR
28/8/03 - NR
0
10
20
30
CAEP
40
14/10/03
50
60
m
g
t
70
80
ABR
(CM only)
90
100
ABR
(CM only)
110
Case Study 2
WP ASA 2004
NAL: Dillon, Van Dun, Carter, Gardner-Berry
FREQUENCY (Hz)
250
500
750
1000
1500
2000
3000
4000
6000
8000
ABR
0
28/8/03 - NR
10
15/3/04 - NR
20
30
CAEP
40
14/10/03
50
60
m
g
t
30/3/04
70
80
ABR
(CM only)
90
100
110
ABR
ECochG
15/3/04
(CM only)
ECochG ECochG ECochG ECochG
(abnormal potentials only)
Case Study 2
WP ASA 2004
NAL: Dillon, Van Dun, Carter, Gardner-Berry
FREQUENCY (Hz)
250
500
750
1000
1500
2000
3000
4000
6000
8000
ABR
0
28/8/03 - NR
10
15/3/04 - NR
20
30
CAEP
40
14/10/03
50
60
m
g
t
30/3/04
70
80
ABR
(CM only)
90
100
110
ABR
ECochG
15/3/04
(CM only)
ECochG ECochG ECochG ECochG
VROA
(abnormal potentials only)
29/4/04
Case Study 2
WP ASA 2004
NAL: Dillon, Van Dun, Carter, Gardner-Berry
What we currently
understand & are building on
I
SEE!
Present
Absent
CAEPs are present for
at least 2 out of 3
speech stimuli.
CAEPs are absent for at
least 2 out of 3 speech
stimuli.
Continue with current
management & continue
to monitor closely
Current management path
should be reviewed
immediately. Consider
gain adjustments and/or
potential problems with
speech discrimination even
when sounds are audible.
Future Directions
We plan to follow these babies up so we can perform more detailed assessments on
speech discrimination ability in quiet and noise. These results will be compared to
both their CAEP and ECochG responses to see if predictive patterns can be seen.
NAL: Dillon, Van Dun, Carter, Gardner-Berry
Conclusions
1.
Predict audibility of speech
sounds - is 4FA on PTA:
•
•
<80 dBHL
(hearing aid range)
>80 dBHL
(cochlear implant range)
2. Predict whether auditory
function is significantly
affected
(with the view to look at speech
discrimination ability in the future)
1. For the 8 subjects whose audibility of the
speech stimuli was <=25 dB (either under-fitted or
outside of the aidable range):
• all showed no CAEP response for at least 2/3
stimuli?
2. For the 6 subjects whose audibility of the
speech stimuli was >25 dB:
• 3 subjects showed present CAEP responses
for at least 2/3 stimuli.
• 3 subjects showed absent CAEP responses to
at least 2/3 stimuli.
Preliminary signs of
poor/inconsistent
auditory functional ability
Preliminary signs of
good auditory
functional ability
Preliminary signs of poor
auditory functional ability
OVERALL: Combining CAEPs with PEACH/IT-MAIS may help to highlight those who need
to have their audiological & intervention management reviewed ASAP.
creating sound valueTM
NAL: Dillon, Van Dun, Carter, Gardner-Berry
Some cortical response
measurements not ready for
clinical use yet
To summary
NAL: Dillon, Van Dun, Carter, Gardner-Berry
/Ah/ 2 second duration
0msG.avg
5msG.avg
10msG.avg
20msG.avg
50msG.avg
5.0
2.5
0.0
Offset
Onset
µV
Gap
-2.5
-5.0
-7.5
-350.0
150.0
Kirsty Gardner-Berry
650.0
1150.0
1650.0
ms
2150.0
2650.0
NAL: Dillon, Van Dun, Carter, Gardner-Berry
Indicator of binaural functioning
-9
9
-8
8
-7
7
P2 Amplitude (V)
N1 Amplitude (V)
N1 and P2 cortical amplitudes for /a/
in noise are enhanced when 700 s
inter-ear delay is introduced to noise
in normal listeners (N=8, 19-32 years)
-6
-5
-4
-3
6
5
4
3
-2
2
-1
1
0
-10
-5
0
5
Signal to Noise Ratio
10
delay
no delay
0
-10
-5
0
5
10
Signal to Noise Ratio
NAL: Dillon, Van Dun, Carter, Gardner-Berry
Size of the electrophysiological
“unmasking” effect is correlated
with behavioral MLD (speech
Behavioural versus
Electrophysiologicalat
(Delay-10
versus Non-delay)
MLD
detection
threshold)
dB
SNR
Pearson Correlation: r = -.7631, p = 0.028
Behavioural masking Level DIfference
8.0
95% confidence
7.5
7.0
6.5
6.0
5.5
5.0
4.5
r=-.76, p=.028
4.0
3.5
-2
-1
0
1
2
3
4
5
Difference in N1P2 Amplitude at -10 dB SNR (V)
NAL: Dillon, Van Dun, Carter, Gardner-Berry
Summary
Cortical responses
– Evaluate the audibility of speech sounds
– Indicate the maturity of the auditory system
– Estimate hearing thresholds when the
patient is awake (adults)
– Automatic detection as good as experts
– Residual noise size critical
NAL: Dillon, Van Dun, Carter, Gardner-Berry
Thanks for listening
www.nal.gov.au
NAL: Dillon, Van Dun, Carter, Gardner-Berry
The HEARing CRC Member Organisations
This research was financially supported by the HEARing CRC
established and supported under the Australian Government’s
Cooperative Research Centres Program
NAL: Dillon, Van Dun, Carter, Gardner-Berry
Title
First
fitting
NAL: Dillon, Van Dun, Carter, Gardner-Berry
Title
2nd
fitting
NAL: Dillon, Van Dun, Carter, Gardner-Berry
Title
3rd at 65
NAL: Dillon, Van Dun, Carter, Gardner-Berry
Title
3rd at 55
NAL: Dillon, Van Dun, Carter, Gardner-Berry
Title
NAL: Dillon, Van Dun, Carter, Gardner-Berry