Transcript HEARLab training - Frye Electronics, Inc.

HEARLab training
Harvey Dillon, Bram Van Dun, Lyndal Carter, Kirsty Gardner-Berry
HEARing CRC
National Acoustic Laboratories (NAL)
With thanks to John Seymour, Suzanne Purdy,
Maryanne Golding, Hsiuwen Chang, Barry Clinch, Lars Kirk
3 September 2010 - Version 1
www.hearingcrc.org
NAL: Dillon, Van Dun, Carter, Gardner-Berry
INTRODUCTION
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
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
FUNDAMENTALS
OF
CORTICAL
RESPONSES
NAL: Dillon, Van Dun, Carter, Gardner-Berry
The end of the road
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Auditory cortex orientation
NAL: Dillon, Van Dun, Carter, Gardner-Berry
Auditory cortex orientation
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Auditory cortex orientation
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+
+
Hudson, 2009
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
Cortical responses in infants with
normal hearing
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
Infant CAEPs to various stimuli
+
/t/ black
/g/ blue
/m/ green
500 Hz red
2000Hz pink
5µV
--
-100
0
100
200
300
400
500
NAL: Dillon, Van Dun, Carter, Gardner-Berry
P1 Latency
Babies latency P1 (N = 20)
Latency (ms)
250
240
+/-SE
C3
230
Cz
C4
220
210
200
190
180
170
500 Hz
2000 Hz
mae
gae
tae
Stimulus
Repeated measures ANOVA (N= 20)
stimulus (p<.0001), montage (n.s.), stimulus x montage (p=0.0223)
NAL: Dillon, Van Dun, Carter, Gardner-Berry
P1 amplitude
Babies amplitude P1 (N = 20)
16
Amplitude (microvolts)
14
12
10
8
+/ SE
C3
6
Cz
4
C4
2
500 Hz
2000 Hz
mae
gae
tae
Stimulus
Repeated measures ANOVA (N= 20)
stimulus (p<.0001), montage (p = 0.0006), stimulus x montage (n.s.)
NAL: Dillon, Van Dun, Carter, Gardner-Berry
Latency versus age
Scatterplot (P1 latency and age combined.sta 10v*281c)
Function = =271-106*log10(x) -7.8*(log10(x))^2+6.94*(log10(x))^3
320
300
Includeetv9="Sharma"
Sharma
al.
Include
NAL
datav9="NAL_Inf_FDA"
1
Include
NAL
datav9="NAL"
2
280
260
240
P1 latency (ms)
220
200
180
160
140
120
100
80
60
40
20
0.6
2.0
0.8
6.0
4.0
20.0
8.0
60.0
40.0
80.0
200.0
600.0
400.0 800.0
Age (months)
NAL: Dillon, Van Dun, Carter, Gardner-Berry
HEARLAB: TECHNICAL
OVERVIEW
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
1. Electrodes
• HEARLab active electrodes
• Poor electrode contact leads to poor quality responses
NAL: Dillon, Van Dun, Carter, Gardner-Berry
In combination with:
Ambu Blue Sensor N
disposable electrodes
NAL: Dillon, Van Dun, Carter, Gardner-Berry
2. Differential Amplification
•
Two electrodes detect the “response (signal)” to
varying degrees plus “noise”, with reference to a
third electrode,
•
By inverting the electrical activity at one of the
two main sites, and finding the difference between
them, some noise cancellation occurs and the
signal size is increased,
•
This improves the signal-to-noise ratio (SNR) to
some degree.
NAL: Dillon, Van Dun, Carter, Gardner-Berry
2. Differential amplification
Non-inverting
+
Inverting
Ground
From: Hall, J.W. (1992) Handbook of Auditory Evoked Potentials
(Excerpts from Figure 5-13)
Electrode input:
+
-
Ground
Pre-amp
Active
Non-inverting
Reference
Inverting
Ground
Reference
NAL: Dillon, Van Dun, Carter, Gardner-Berry
3. Averaging
Averaging is the single most powerful technique for
improving SNR
For repeated auditory stimulation, the neurons of
the auditory system will be activated in the same
sequence, at the same point in time,
We can say then that this neuronal activity is
“time-locked” to the presentation of the stimulus.
NAL: Dillon, Van Dun, Carter, Gardner-Berry
3. Averaging
NAL: Dillon, Van Dun, Carter, Gardner-Berry
3. Averaging
• Repeated stimulation with the same sound is required
to view the auditory response (i.e., to have an adequate
signal-to-noise ratio),
• The number of stimulations required depends on the
size (i.e., amplitude) of the response.
NAL: Dillon, Van Dun, Carter, Gardner-Berry
4. Filters
• A device which permits some frequencies through
and not others,
• High Pass (low freq) filters reject lower energy and
Low Pass (high freq) reject energy above.
The most appropriate filters are those which preserve the
frequency region of the response and exclude others
NAL: Dillon, Van Dun, Carter, Gardner-Berry
4. Filters
NAL: Dillon, Van Dun, Carter, Gardner-Berry
5. Stimuli
• Choice of stimulus depends on our clinical objective and
from where in the auditory system we are recording.
• Responses from the early parts of the auditory system
are best generated using very brief stimuli such as a
“click”. Responses from late in the auditory system can
be generated using tones, speech sounds or clicks.
• Stimuli may be delivered by headphone, insert earphone,
bone conduction or loud speaker.
NAL: Dillon, Van Dun, Carter, Gardner-Berry
5. Stimuli
Three speech sounds: /m/ /g/ /t/
70
5
10
15
Time (ms)
M
20
25
30
1
0
5
10
15
Time (ms)
T
20
25
30
1
/m/
40
/g/
30
/t/
20
10
5
10
15
Time (ms)
20
25
30
8000
5000
3150
2000
1250
800
500
0
0
-1
0
50
315
-1
0
60
200
-1
0
1/3 octave spectra (dB SPL)
0
125
Amplitude
Amplitude
Amplitude
G
1
Frequency (Hz)
NAL: Dillon, Van Dun, Carter, Gardner-Berry
Automatic detection of cortical
responses
NAL: Dillon, Van Dun, Carter, Gardner-Berry
Why automated method?
•
•
•
•
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
Response detection (Hotelling’s T2)
Stim
onset
Time
•
Each response* is divided into 50 ms time bins (50 – 500 ms)
•
The data points are averaged within each time bin to form 9 variables
NAL: Dillon, Van Dun, Carter, Gardner-Berry
Response detection (Hotelling’s T2)
Calculates the probability that a mean value of
any linear combination of the 9 variables was
significantly different from zero.
Hotelling’s T2 is :
At least equal to, if not more able, than the “composite”
examiner to differentiate a CAEP from random noise at
sensation levels of 10 dB or more
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
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
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
CLINICAL USE OF
HEARLAB
NAL: Dillon, Van Dun, Carter, Gardner-Berry
Equipment configuration and
test environment
NAL: Dillon, Van Dun, Carter, Gardner-Berry
Equipment configuration
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
Calibration
Calibrate each time major changes occur in test environment.
For details refer to HEARLab manual, Section 4.1
NAL: Dillon, Van Dun, Carter, Gardner-Berry
Ambient noise measurement
In general the ambient noise level should not exceed 35 dB A.
For details refer to HEARLab manual, Section 5.3.3
NAL: Dillon, Van Dun, Carter, Gardner-Berry
Test environment
(highlights from HEARLab manual, Appendix A:
‘Practical aspects of CAEP testing with infants’)
• Make the test environment ‘child friendly’.
• Provide a chair that is big enough for both parent and child.
• Use washable covers/towels on the chair.
• Have a separate container on hand to collect items that require cleaning.
• Avoid fluorescent lighting, cell phones.
• Do not place mains-powered devices close to the child.
• Place floor markers indicating the position of equipment after calibration.
NAL: Dillon, Van Dun, Carter, Gardner-Berry
Before the appointment
NAL: Dillon, Van Dun, Carter, Gardner-Berry
Before the appointment
(highlights from HEARLab manual, Appendix A:
‘Practical aspects of CAEP testing with infants’)
• Provide parents with information. This will save time during the assessment.
• Ask about the child’s sleeping routines. They should be awake during testing.
• Dress the child with layers of clothing that can be easily removed.
NAL: Dillon, Van Dun, Carter, Gardner-Berry
Preparation for testing
NAL: Dillon, Van Dun, Carter, Gardner-Berry
From: Hall, J.W. (1992) Handbook of Auditory Evoked Potentials
NAL: Dillon, Van Dun, Carter, Gardner-Berry
Electrode equipment
NAL: Dillon, Van Dun, Carter, Gardner-Berry
Keeping electrodes on the baby
using a headband
NAL: Dillon, Van Dun, Carter, Gardner-Berry
Preparation for testing
(highlights from HEARLab manual, Appendix A:
‘Practical aspects of CAEP testing with infants’)
• Have all equipment ready before the child arrives.
• Change hearing aid batteries and check operation.
• Ask parents to switch off mobile phones.
• Connect to the child and don’t physically ‘stand over’ the child while doing skin prep.
• Prepare the skin firmly but not too hard with cotton bud and medical gel.
• Alcohol wipes is not needed and not recommended for delicate infant skins.
• A headband can be very helpful for keeping electrodes in place.
• Avoid contact of electrode cables with child as (s)he may pull them away.
NAL: Dillon, Van Dun, Carter, Gardner-Berry
Conducting a measurement
NAL: Dillon, Van Dun, Carter, Gardner-Berry
HEARLab
Two options:
 ACA: “Aided Cortical Assessment”
• Free field
• Speech sounds
• Can be tested aided or unaided
• Focused on infants
 CTE: “Cortical Threshold Evaluation”
• With insert phones
• Tone-bursts
• Only unaided
• Focused on adults
NAL: Dillon, Van Dun, Carter, Gardner-Berry
Starting up HEARLab
Double click icon
More detailed information
in HEARLab manual,
Chapter 3.
First screen that pops up:
NAL: Dillon, Van Dun, Carter, Gardner-Berry
Adding a new client
NAL: Dillon, Van Dun, Carter, Gardner-Berry
Searching for a client
NAL: Dillon, Van Dun, Carter, Gardner-Berry
New assessment
NAL: Dillon, Van Dun, Carter, Gardner-Berry
Configuring ACA
NAL: Dillon, Van Dun, Carter, Gardner-Berry
Configuring ACA
NAL: Dillon, Van Dun, Carter, Gardner-Berry
New run
NAL: Dillon, Van Dun, Carter, Gardner-Berry
Impedance check
NAL: Dillon, Van Dun, Carter, Gardner-Berry
Acquisition of data
NAL: Dillon, Van Dun, Carter, Gardner-Berry
Acquisition of data
detection of response
NAL: Dillon, Van Dun, Carter, Gardner-Berry
Acquisition of data
Cumulative averages
p-value automatic detection
of response
Most recent epoch
Ongoing EEG
NAL: Dillon, Van Dun, Carter, Gardner-Berry
Acquisition of data
p-value automatic
detection
p-values must be < 0.05
for detection of cortical
! This means that in 5% of the cases
a false detection is possible !
Residual noise level
The indicator lights
should be GREEN
before concluding
no cortical response
exists
NAL: Dillon, Van Dun, Carter, Gardner-Berry
Result window
NAL: Dillon, Van Dun, Carter, Gardner-Berry
Result window
Were responses detected?
Averaged responses
Statistical analysis
history
NAL: Dillon, Van Dun, Carter, Gardner-Berry
Distraction techniques
(highlights from HEARLab manual, Appendix A:
‘Practical aspects of CAEP testing with infants’)
• Do not obstruct the line of sight to the loudspeaker when testing free field.
• Only use noiseless toys, appropriate to the age, and which are easily cleanable.
• Try to keep children awake, but not too active.
• DVDs on a screen! Bubbles! Following slides will show a lot of distraction items.
• Eating and drinking is possible, including breast feeding.
• If the child is quiet, the distractor can move out of sight.
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
Head support
Yes!!
NAL: Dillon, Van Dun, Carter, Gardner-Berry
Cortical threshold estimation
- is very similar to ACA
- has not been verified clinically with infants yet
NAL: Dillon, Van Dun, Carter, Gardner-Berry
Finishing up
NAL: Dillon, Van Dun, Carter, Gardner-Berry
Finishing up
• Results can be printed.
• Follow infection guidelines to wash or dispose of used equipment.
NAL: Dillon, Van Dun, Carter, Gardner-Berry
INTERPRETATION OF
THE RESULTS
&
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
Good agreement between CAEP and
audiometric thresholds in awake adults
Tsui, Wong & Wong 2002
NAL: Dillon, Van Dun, Carter, Gardner-Berry
Cortical threshold vs behavioural
outliers in about
threshold - adults
7% of threshold
estimates!
(reported by
several studies)
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
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
• About 7% overestimates hearing thresholds
severely (by 20 dB or more).
• 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
Detection of corticals in infants
However, some caution is recommended.
For speech sounds exceeding 10 dB Sensation Level
 23% of evoked corticals are NOT present / detected
This means that any audiological decisions should not
be made based on cortical measurements alone!
NAL: Dillon, Van Dun, Carter, Gardner-Berry
CASE STUDIES
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
implants 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 moving all the time.
NAL: Dillon, Van Dun, Carter, Gardner-Berry
At her quietest state, but this only lasted for
a few seconds.
NAL: Dillon, Van Dun, Carter, Gardner-Berry
Case 6
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
Auditory neuropathy
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
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
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)
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
WP ASA 2004
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