Download Hearing Threshold Estimation in Infants Using Auditory Steady

J Am Acad Audiol 16:291–300 (2005)
Hearing Threshold Estimation in Infants
Using Auditory Steady-State Responses
Gary Rance*
Richard Roper†
Lindsay Symons‡
Lisa-Jane Moody§
Christine Poulis**
Melissa Dourlay††
Therese Kelly‡‡
Abstract
Successful early intervention in children with permanent hearing loss requires
assessment techniques that can accurately reflect the behavioral audiogram
in infancy. This retrospective study compared auditory steady-state response
(ASSR) findings from subjects tested in the first three months of life with
subsequently obtained behavioral hearing levels. ASSR audiograms were
established using amplitude and frequency modulated tones at octave
frequencies (500 Hz to 4 kHz). Results obtained from 575 subjects including
285 with normal hearing, 271 with sensorineural hearing loss, and 19 with
auditory neuropathy-type hearing loss are presented. ASSR and behavioral
hearing thresholds for subjects in the normal and sensorineural groups were
highly correlated, with Pearson r values exceeding 0.95 at each of the test
frequencies. In contrast, ASSR thresholds in children with AN-type hearing loss
did not accurately reflect the behavioral audiogram. Overall, the findings
indicate that ASSR testing can offer useful insights into the hearing acuity of
children tested in infancy.
Key Words: Auditory steady-state response, hearing, infants
Abbreviations: ABR = auditory brainstem response; AN = auditory neuropathy;
ASSR = auditory steady-state response; NICU = neonatal intensive care unit
Sumario
Una intervención temprana exitosa en niños con trastornos auditivos exige
técnicas que puedan reflejar con exactitud un audiograma conductual en la
infancia. Este estudio retrospectivo compara los hallazgos con respuestas
auditivas de estado estable (ASSR) de sujetos evaluados en los primeros tres
meses de vida, con los niveles auditivos conductuales obtenidos
subsecuentemente. Se establecieron audiogramas por ASSR utilizando tonos
modulados en frecuencia y amplitud por octava (500 Hz a 4 khz). Se presentan
los resultados obtenidos de 575 sujetos, incluyendo 285 con audición normal,
271 con hipoacusia sensorineural y 19 con pérdidas auditivas tipo neuropatía
auditiva. Los umbrales de ASSR y los umbrales auditivos conductuales en los
grupos de sujetos con audición normal y con hipoacusia sensorineural tuvieron
una alta correlación, con valores Pearson por encima de 0.95 en cada una
de las frecuencias evaluadas. En contraste, los umbrales ASSR en niños con
hipoacusia tipo AN no reflejaron con exactitud el audiograma conductual.
Globalmente, los hallazgos indican que la evaluación con ASSR puede ofrecer
*Department of Otolaryngology, University of Melbourne; †Ballarat Hearing Centre; ‡Shepparton Hearing Centre; §Geelong
Hospital; **Royal Children’s Hospital (Melbourne); ††Monash Medical Centre; ‡‡Taralye—The Oral Language Centre for Deaf
Children
Gary Rance, University of Melbourne, School of Audiology, 172 Victoria Parade, East Melbourne 3002, Australia; Phone:
61-3-9929-8740; Fax: 61-3-9929-3312; E-mail: [email protected]
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una perspectiva útil con relación a la agudeza auditiva de aquellos niños
evaluados en la infancia.
Palabras Clave: Respuestas auditivas de estado-estable, audición, infantes
Abreviaturas: ABR = Respuesta auditivas del tallo cerebral; AN = neuropatía
auditiva; ASSR = Respuestas auditivas de estado-estable; NICU = unidad de
cuidados intensivos neonatal
R
ecent evidence has confirmed the longheld belief that early diagnosis and
intervention can ameliorate the
damaging effects of congenital hearing loss.
Studies by Yoshinaga-Itano et al (1998) and
Moeller (2000), for example, have shown that
the provision of appropriate amplification
and educational support within the first six
months of life maximizes the potential for
long-term speech and language development
in children with all degrees of permanent
hearing loss. Determination of this critical
intervention period (zero to six months) has
provided an impetus for the establishment of
universal neonatal and infant hearing
screening programs worldwide whose aim is
to identify affected youngsters within the
first few weeks of life. However, identification
is only the first step in the successful
management of a hearing-impaired child.
Intervention processes, in particular the
fitting of appropriate hearing aids, require
audiometric profiles that accurately reflect
both the degree and configuration of a child’s
hearing loss. As behavioral hearing measures
in children less than six months of age cannot
provide this information (Davis et al, 1991;
Ling et al, 1970), nonvolitional assessment
procedures such as those based upon auditory
evoked potentials have become the tests of
choice for this age group.
The auditory steady-state response
(ASSR) is one such evoked potential whose
applicability for the assessment of hearing in
infants and young children has been
investigated over the past decade (Rickards
et al, 1994; Aoyagi et al, 1999; Cone-Wesson,
292
Parker, et al, 2002; Cone-Wesson, Rickards,
et al, 2002; Rance and Briggs, 2002; Rance
and Rickards, 2002). Auditory steady-state
responses are scalp potentials that can be
elicited in response to periodically varying
stimuli such as sinusoidal amplitude and/or
frequency modulated tones. The resulting
response is periodic and is phase locked to the
modulation envelope of the stimulus tone.
ASSRs can be obtained for a wide range of
modulation frequencies (Rickards and Clark,
1984), but rates around 70 to 100 Hz have
proven most successful for assessment of
sleeping babies (Levi et al, 1993; Rickards et
al, 1994).
Auditory steady-state response testing
using modulated tones has a number of
advantages in estimating the behavioral
audiogram over techniques that require short
duration stimuli (such as the auditory
brainstem response). The continuous nature
of the tones means that they do not suffer the
spectral distortion problems associated with
acoustic clicks or tone bursts. As such, they
are reasonably frequency-specific and allow
the generation of an “evoked potential
audiogram” that can reflect the pattern of a
subject’s hearing thresholds (Rance et al,
1995; Lins et al, 1996; Aoyagi et al, 1999).
Another particular advantage afforded by
the continuous stimulus is that the tone can
be presented at high levels (up to 120 dBHL
at most test frequencies) enabling assessment
of ears with only minimal amounts of residual
hearing (Rance et al, 1998; Stueve and
O’Rourke, 2003; Swanepoel et al, 2004).
Auditory steady-state responses can be
H e a r i n g T h r e s h o l d E s t i m a t i o n i n I n f a n t s U s i n g A S S R s /Rance et al
recorded in sleeping subjects of all ages
(Aoyagi et al, 1993; Rickards et al, 1994;
Cone-Wesson, Parker, et al, 2002). Stimuli
modulated at rates around 70–100 Hz have
been shown to elicit potentials (with
equivalent latencies of approximately 10
msec) in normally hearing neonates at levels
around 25–40 dBHL. Auditory steady-state
responses have also been studied in young
children with varying degrees of
sensorineural hearing loss (Rance et al, 1995,
1998; Lins et al, 1996; Aoyagi et al, 1999;
Rance and Briggs, 2002; Rance and Rickards,
2002; Vander Werff et al, 2002; Stueve and
O’Rourke, 2003; Swanepoel et al, 2004). ASSR
thresholds in these investigations have been
highly correlated with behavioral hearing
levels and have typically been obtained at low
sensation levels (≈ 5–10 dB).
This retrospective clinical study further
investigates the relationship between ASSR
and behavioral hearing thresholds in young
children. In particular it involves a
comparison of ASSR findings obtained in
infancy with subsequently established
behavioral hearing levels for a group of 575
children with hearing thresholds ranging
from normal to profound levels. Results for
ears with normal hearing, sensorineural
hearing loss, and auditory neuropathy-type
hearing loss are presented.
METHODS
C
linical findings from the seven
metropolitan and regional diagnostic
audiology clinics in the state of Victoria
(Australia) with ASSR assessment capabilities
are presented in this study.1 Identical test
procedures were employed in these centers,
and in each case, the auditory steady-state
response assessments were undertaken using
either the ERA Systems, or GSI AUDERA®‚
commercial evoked potential devices. The data
represents results obtained for every young
child who underwent ASSR testing at these
centers (and who met the selection criteria)
over a five-year period from 1998 to 2003.
Subjects were included in the study if
they had undergone the ASSR assessment at
an (corrected) age of ≤3 months and if they
had subsequently shown reliable hearing
thresholds when tested using conditioned
audiometric procedures. In order to reduce the
effect of fluctuating hearing levels on the
results, children with evidence of middle ear
abnormality were excluded. Each of the
subjects included in the analysis showed
normal multiple probe tone tympanometric
results on each of the test occasions and no
significant air-bone gap at any test frequency
on the occasion of their behavioral hearing
assessment.
Results from 575 infants and young
children (1091 ears) were included in the
analysis. ASSR thresholds at a range of test
frequencies were established in each of these
subjects between the (corrected) ages of 0.5
and 3 months (mean: 2.6 months). ASSR
testing was performed in sound-treated
rooms with the child in natural sleep.
Electroencephalographic activity was
measured using either Nikomed or Neuroline
neonatal electrodes. Differential recordings
were made between electrodes placed on the
high forehead (Fz) or vertex (Cz) and the
ipsilateral mastoid or earlobe. A third electrode
placed on either the low forehead or
contralateral mastoid served as a ground.
Interelectrode impedance was minimized using
abrasive skin preparation materials, and was
typically ≤5kΩ at 260 Hz. Data was excluded
if impedance values exceeded 10 kΩ.
The test stimuli were single 500 Hz, 1
kHz, 2 kHz, and 4 kHz tones amplitude and
frequency modulated at rates between 74 Hz
and 95 Hz.2 This modulation range was used
to avoid the problems associated with ASSR
testing at lower rates (<70 Hz) in sleeping
pediatric subjects (Levi et al, 1993).
Amplitude modulation (depth 100%) and
frequency modulation (width 10% of the
carrier tone) were combined to maximize
response amplitude (Rickards et al, 1994).
Auditory steady-state response analysis
was carried out in the manner described
by Cohen et al (1991). The raw
electroencephalogram was passed through
a preamplifier, bandpass filtered (10 Hz–500
Hz), and then Fourier analyzed at the
stimulus modulation frequency to extract
response phase and amplitude information.
The presence or absence of a response was
then determined automatically with a
statistical detection criterion based on
nonrandom phase behavior (phase coherence).
Auditory steady-state response
thresholds were established for each test
frequency by increasing or decreasing the
stimulus presentation level in 10 dB steps
from a starting point around 60 dBHL. Once
an approximate minimum response level was
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established, further testing in 5 dB steps
was carried out. The threshold was defined
as the softest level at which the phase
coherence was statistically significant at the
p < 0.03 level. Where possible, thresholds
were established at the four carrier
frequencies in each ear. This assessment
typically required a test time of between 30
and 45 minutes. As the testing was carried out
with the subject in natural sleep, it was not
always possible to obtain a complete data set.
Behavioral hearing threshold levels were
established using age-appropriate (visual
response audiometry) assessment techniques
in sound-treated test rooms. The corrected age
of the subjects at the time of the testing
ranged from 6 months to 23 months (mean:
9.8 months). These assessments were carried
out by experienced pediatric audiologists,
and results were only included in the analysis
if they were considered to be reliable. The test
stimuli were warble tones at octave
frequencies from 500 Hz to 4 kHz and were
presented monaurally via headphones or
tubephones. The maximum presentation level
was 120 dBHL for all frequencies.
R E S U LT S
Normal-Hearing Subjects
Two hundred and eighty-five of the
subjects who underwent ASSR evaluation in
infancy subsequently showed behavioral
hearing thresholds within the normal
audiometric range (i.e., conditioned hearing
thresholds ≤15 dBHL). The mean and
standard deviation of the ASSR thresholds
obtained at each test frequency in these
children is shown in Table 1. Mean ASSR
threshold levels ranged from 24.3 dBHL to
32.5 dBHL. In addition, Table 1 shows the
ASSR/behavioral hearing threshold difference
levels for each ear at each carrier frequency.
(Difference values were determined by
subtracting the behavioral hearing threshold
from the ASSR threshold at each test
frequency). In this case the mean difference
values for the various carrier tones ranged
from 22.4 dB to 31.0 dB.
The stimulus sensation level required to
elicit the ASSR varied with carrier frequency
in this group of normally hearing infants.
Analysis of variance showed a significant
difference across test frequencies (F = 87.15;
p < 0.001), and post hoc analysis revealed that
while the ASSR/behavioral hearing threshold
differences at the 500 Hz and 1 kHz test
frequencies were not different from each
other, the threshold difference levels at these
frequencies were significantly higher than
those obtained at both the 2 kHz and 4 kHz
test frequencies (p < 0.05). Furthermore,
ASSR thresholds at 4 kHz were obtained at
significantly higher sensation levels than
those at the 2 kHz test frequency (p < 0.05).
Results for Subjects with
Sensorineural Hearing Loss
Two hundred and seventy-one of the
children evaluated in this study were shown
to have sensorineural-type hearing loss in one
or both ears. Results for these children were
combined with those of the normally hearing
group and were subjected to correlation and
regression analysis. Overall, the findings
showed a strong correlation between ASSR
threshold and behavioral hearing threshold
levels. Pearson r correlation coefficient values
ranged from 0.96 to 0.98 across the test
frequencies (Table 2).
Figure 1 shows the distribution of
ASSR/behavioral hearing threshold
comparisons for all of the normally hearing and
sensorineural hearing loss subjects at each of
the test frequencies. Two thousand nine
hundred and forty-three comparisons were
included in the analysis: 715 at 500 Hz, 692
Table 1. ASSR Threshold Levels and ASSR/Behavioral Threshold Difference Levels for Normally
Hearing Subjects at Each of the Test Frequencies
Test Frequency
500 Hz
1 kHz
2 kHz
4 kHz
ASSR Threshold
Mean (dB)
Std Dev (dB)
32.3
7.5
32.5
6.6
24.3
6.3
28.1
7.5
Difference Level
Mean (dB)
Std Dev (dB)
30.4
6.7
31.0
6.2
22.4
6.7
27.5
7.5
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Table 2. Pearson Product Moment Correlation Coefficient Values Comparing ASSR and Behavioral
Hearing Thresholds
Test Frequency
500 Hz
1 kHz
2 kHz
4 kHz
Normal/Sensorineural Group
0.96
0.97
0.98
0.98
Auditory Neuropathy Group
0.54
0.49
0.55
0.46
at 1 kHz, 701 at 2 kHz, and 835 at 4 kHz.
ASSR thresholds in the sensorineural
hearing loss subjects were typically obtained
at levels slightly higher than the behavioral
hearing levels. How much higher was related
to the degree of the child’s loss. This finding
is reflected in the linear regression lines that
have been fit to the data for the various
carrier frequencies. In each case the slope of
less than unity indicates that ASSR
thresholds tended to be closer to hearing
threshold as the degree of hearing loss
increased.
A
C
Of the five hundred and fifty-six subjects
with either normal hearing or sensorineural
hearing loss, only four showed ASSR
thresholds at levels >10 dB lower than their
subsequently established behavioral
thresholds. In each of these cases, there was
evidence of significant deterioration in
hearing level in the time between the ASSR
and behavioral hearing assessments. Repeat
ASSR evaluation in each instance showed
results that corresponded with the
audiogram.3 Results for these children were
not included in the statistical analysis and are
B
D
F i g u r e 1 . Distribution of ASSR/behavioral hearing threshold comparisons for ears with normal hearing or sensorineural-type hearing loss. Dashed lines represent 1:1 ASSR-behavioral correspondence. The solid lines are
the linear regression lines. The regression formula for each frequency is shown.
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F i g u r e 2 . ASSR and behavioral audiograms for a child with sensorineural hearing loss following viral
meningitis. (A) ASSR thresholds at two months of age (18 days post infection). (B) Conditioned audiometric
thresholds obtained at six months of age (ASSR thresholds at two months). (C) ASSR and behavioral hearing
thresholds obtained at ninth months of age. (D) ASSR and behavioral hearing thresholds at 26 months of age.
represented by filled circles in Figure 1.
Auditory Neuropathy Subjects
Case Study
Nineteen of the children evaluated in
this study presented with auditory
neuropathy (AN)-type hearing loss. Auditory
neuropathy is a disorder in which cochlear
amplification (outer hair cell) function is
normal but afferent neural conduction in the
auditory pathway is disrupted (Starr et al,
1996). Each of the auditory neuropathy
subjects fit the typical clinical AN pattern in
that they showed absent auditory brainstem
responses (ABRs) to acoustic clicks at
maximum presentation levels but had present
outer hair cell responses including otoacoustic
emissions and cochlear microphonics (Rance
et al, 1999).
The distribution of ASSR/behavioral
Figure 2 shows examples typical of the
way in which ASSR thresholds mirrored the
behavioral audiogram in the babies with
sensorineural hearing loss assessed in this
study. Audiograms A-D track the partial
hearing recovery that occurred over a 12month period in a young subject who suffered
a bout of viral meningitis at one month of age.
The repeat assessments in this example
reflect the changing degree and configuration
of the hearing loss and show the utility of the
ASSR procedure for the evaluation of ears
with only minimal amounts of residual
hearing.
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H e a r i n g T h r e s h o l d E s t i m a t i o n i n I n f a n t s U s i n g A S S R s /Rance et al
A
B
C
D
F i g u r e 3 . Distribution of ASSR/behavioral hearing threshold comparisons for ears with auditory neuropathytype hearing loss. Dashed lines represent 1:1 ASSR-behavioral correspondence.
hearing threshold comparisons for children
with auditory neuropathy-type hearing loss is
shown in Figure 3. Unlike the findings for
children with sensorineural hearing loss, ASSR
responses in the AN subjects were typically
only obtained at high sensation levels, and
ASSR threshold levels showed only a weak
correlation with the behavioral audiogram.
Pearson r correlation coefficients for this group
ranged from 0.46 to 0.55 (Table 2).
DISCUSSION
T
he mean ASSR threshold sensation levels
for normally hearing babies in this study
were in the range 22 to 30 dBHL. This result
is consistent with previously reported findings
for infant subjects. Lins et al (1996) used a
“4-carrier frequency” combined ASSR
technique to determine response threshold in
a group of (presumed normal) subjects with
a similar age range (1–10 months), and also
found mean ASSR thresholds of around 20–30
dBHL. As in the present study, the Lins et al
(1996) data also showed a significant effect
of carrier frequency with ASSR thresholds
obtained at significantly lower levels for highfrequency stimuli than for low frequencies.
This pattern can also be seen in the findings
of a large-scale study of ASSR thresholds in
newborn subjects reported by Rickards et al
(1994) where the mean response threshold at
500 Hz was approximately 10 dB higher than
those obtained for stimuli in the highfrequency range. The high-frequency
advantage reported in these studies is
consistent with the findings of Cohen et al
(1991) that high-frequency tones elicit
comparatively larger ASSR amplitudes in
sleeping subjects and may reflect the greater
neural synchronization of responses from the
basal cochlear turn.
The ASSR threshold levels obtained for
the 0.5- to 3-month-old subjects in this study
were lower than those reported previously for
normal neonates. Rickards et al (1994) used
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similar test parameters and procedures to
those of the present study and found higher
mean ASSR threshold levels at each of the
common test frequencies. The difference in
ASSR threshold between the studies was
particularly evident for the 500 Hz test
frequency where thresholds obtained in the
newborns were typically 10 dB higher than
those obtained for the slightly older infants
described in this paper. While the effect of
extraneous factors such as the fluctuating
middle ear status of the neonates and test
environment differences cannot be
discounted, the findings do point to
developmental changes in ASSR threshold
occurring in the first weeks of life.
Overall, the ASSR thresholds for the
normally hearing cohort in this investigation
were significantly higher than those reported
for the tone-burst auditory brainstem
response (TB-ABR) technique. Assessment
using toneburst ABR is currently the best
alternative to the ASSR procedure for
frequency specific assessment of hearing in
young children. Mean toneburst ABR
thresholds have been obtained in both
neonatal (Sininger et al, 1997) and infant
(Stapells et al, 1995) subjects at levels 10–20
dB lower than seen for ASSR testing in this
study. Why the discrepancy between these
two
auditory
brainstem-based
electrophysiological techniques should occur
is a matter for further investigation. What is
clear is that ASSR testing (as carried out in
this study) cannot reliably differentiate
between normal ears and those with mildly
elevated hearing levels. The accuracy of the
technique does, however, improve
dramatically in ears with sensorineural
hearing loss.
For the children with sensorineural
hearing loss in this study, there was a strong
relationship between the ASSR thresholds
obtained in infancy and their subsequently
established audiograms. The results described
in Figure 2 are typical of those obtained in
this subject group with the ASSR threshold
pattern reflecting both the degree and
configuration of the hearing loss. The
audiograms shown in Figure 2 also reflect one
of the particular advantages of ASSR
assessment in subjects with only minimal
amounts of residual hearing. The continuous
tones used to elicit the ASSR resemble the
stimuli used in clinical behavioral testing
and can be presented at higher levels than is
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possible for brief stimuli such as acoustic
clicks or tone bursts. (Brief stimuli require a
calibration correction to account for temporal
summation differences between short- and
long-duration signals). As such, the ASSR
technique is well suited to quantification of
hearing loss in the severe to profound range.
Overall, the results of this study are
consistent with those reported previously for
infants and young children with
sensorineural hearing loss (Rance et al, 1995,
1998; Lins et al, 1996; Aoyagi et al, 1999;
Rance and Briggs, 2002; Rance and Rickards,
2002; Vander Werff et al, 2002; Stueve and
O’Rourke, 2003; Swanepoel et al, 2004) and
indicate that ASSR testing in the first few
months of life can offer information accurate
enough to form a basis for hearing aid fitting
and early intervention.
The results obtained for subjects with
auditory neuropathy-type hearing loss, in
contrast, indicate that the ASSR technique in
such cases cannot be used to predict the
behavioral audiogram. That the typical
ASSR/behavioral hearing threshold
relationship should be disrupted in these
children is not surprising. Any attempt to
estimate hearing levels on the basis of evoked
potential findings (ASSR or otherwise) is
based on the assumption that the subject’s
auditory pathway is normal and that an
elevation in response threshold reflects a
reduction in the sensitivity of the peripheral
(middle ear/cochlear) hearing mechanism.
In the case of auditory neuropathy, this
assumption is violated as affected subjects
show evidence of normal cochlear (outer hair
cell) function but disordered neural
conduction through the auditory pathway
(Starr et al, 1996). The results obtained in this
study are consistent with those reported
previously (Rance et al, 1999; Rance and
Briggs, 2002) and indicate that evoked
potentials arising in the auditory
brainstem/midbrain (such as the ASSR to
high rate stimuli) are severely affected in
cases of auditory neuropathy and cannot be
used to predict hearing levels.
Clearly, interpretation of elevated ASSR
thresholds requires an understanding of the
type of hearing loss affecting the subject.
ASSR testing, which involves assessment in
the frequency domain, cannot differentiate
between peripheral (cochlear) hearing losses
and those that are related to neural
transmission or retrocochlear abnormalities.
H e a r i n g T h r e s h o l d E s t i m a t i o n i n I n f a n t s U s i n g A S S R s /Rance et al
As such, it is clinically important (particularly
in neonatal intensive care unit [NICU]
graduates who make up a high proportion of
pediatric cases with auditory pathway
disorders) to consider ASSR findings in
conjunction with the results of other measures
of auditory system function such as
otoacoustic emissions, cochlear microphonics,
and behavioral observation (Rance et al,
1999; Cone-Wesson, Parker, et al, 2002).
S U M M A RY
E
stablishment of universal hearing
screening programs around the world
has allowed identification of impaired
children in the neonatal period. The results
of this clinical study indicate that ASSR
assessment can offer a useful next step in the
evaluation process for these early-identified
youngsters, in most cases allowing the
behavioral audiogram to be predicted and
intervention processes to be implemented.
NOTES
1. The participating audiology centers were the
University of Melbourne, School of Audiology Clinic;
Ballarat Hearing Centre; Taralye—The Oral Language Centre for Deaf Children; Royal Children’s
Hospital (Melbourne); Monash Medical Centre; Geelong Hospital; and the Shepparton Hearing Centre.
2. Modulation rate varied with carrier frequency
as follows: the 500 Hz carrier was modulated at 74
Hz, the 1 kHz carrier at 81 Hz, the 2 kHz carrier at
88 Hz, and the 4 kHz carrier at 95 Hz.
3. The etiologies of these subjects were consistent
with deteriorating hearing. Two of the children had
Enlarged Vestibular Aqueduct Disorder; one child’s
loss was considered to be related to CMV exposure in
utero; and one child had Pendred’s Syndrome.
REFERENCES
Aoyagi M, Kiren T, Suzuki Y, Fuse T, Koike Y. (1993)
Optimal modulation frequency for amplitudemodulation following response in young children
during sleep. Hear Res 65:253–261.
Aoyagi M, Suzuki Y, Yokota M, Furuse H, Watanabe
T, Ito T. (1999) Reliability of 80-Hz amplitudemodulation-following response detected by phase
coherence. Audiol Neurootol 4:28–37.
Cohen LT, Rickards FW, Clark GM. (1991) A
comparison of steady-state evoked potentials to
modulated tones in awake and sleeping humans. J
Acoust Soc Am 90:2467–2479.
Cone-Wesson B, Parker J, Swiderski N, Rickards F.
(2002) The auditory steady-state response: full term
and premature neonates. J Am Acad Audiol
13:260–269.
Cone-Wesson B, Rickards FW, Poulis C, Parker J, Tan
L, Pollard J. (2002) The auditory steady-state
response: clinical observations and applications in
infants and children. J Am Acad Audiol 13:270–282.
Davis AC, Wharrad HJ, Sancho J, Marshall DH.
(1991) Early detection of hearing impairment: what
role is there for behavioral methods in the neonatal
period? Acta Otolaryngol Suppl (Stockh) 482:103–109.
Levi EC, Folsom RC, Dobie RA. (1993) Amplitudemodulation following response (AMFR): effects of
modulation rate, carrier frequency, age and state.
Hear Res 5:366–370.
Ling D, Ling AH, Doering DG. (1970) Stimulus,
response and observer variables in auditory screening
of newborn infants. J Speech Hear Res 13:9–18.
Lins OG, Picton TW, Boucher BL, Durieux-Smith A,
Champagne SC, Moran LM, Perez-Abalo MC, Martin
V, Savio G. (1996) Frequency-specific audiometry
using steady-state responses. Ear Hear 2:81–96.
Moeller MP. (2000) Early intervention and language
development in children who are deaf and hard of
hearing. Pediatrics 106:E43.
Rance G, Beer DE, Cone-Wesson B, Shepherd RK,
Dowell RC, King AK, Rickards FW, Clark GM. (1999)
Clinical findings for a group of infants and young
children with auditory neuropathy. Ear Hear
20:238–252.
Rance G, Briggs RJS. (2002) Assessment of hearing
level in infants with significant hearing loss: the
Melbourne experience with steady-state evoked
potential threshold testing. Ann Otol Rhinol Laryngol
111:22–28.
Rance G, Dowell RC, Beer DE, Rickards FW, Clark
GM. (1998) Steady-state evoked potential and
behavioral hearing thresholds in a group of children
with absent click-evoked auditory brain stem response.
Ear Hear 19:48–61.
Rance G, Rickards FW. (2002) Prediction of hearing
threshold in infants using auditory steady-state
evoked potentials. J Am Acad Audiol 13:236–245.
Rance G, Rickards FW, Cohen LT, De Vidi S, Clark
GM. (1995) The automated prediction of hearing
thresholds in sleeping subjects using auditory steadystate evoked potentials. Ear Hear 16:499–507.
Rickards FW, Clark GM. (1984) Steady-state evoked
potentials to amplitude modulated tones. In: Nodar
RH, Barber C, eds. Evoked Potentials II. Boston:
Butterworth, 163–168.
Rickards FW, Tan LE, Cohen LT, Wilson OJ, Drew JH,
Clark GM. (1994) Auditory steady-state evoked
potentials in newborns. Br J Audiol 28:327–337.
Sininger YS, Abdala C, Cone-Wesson B. (1997)
Auditory threshold sensitivity of the human neonate
as measured by the auditory brainstem response.
Hear Res 104:27–38.
299
J o u r n a l o f t h e A m e r i c a n A c a d e m y o f A u d i o l o g y /Volume 16, Number 5, 2005
Stapells DR, Gravel JS, Martin BA. (1995) Thresholds
for auditory brain stem responses to tones in notched
noise from infants and young children with normal
hearing or sensorineural hearing loss. Ear Hear
16:361–371.
Starr A, Picton TW, Sininger YS, Hood LJ, Berlin
CI. (1996) Auditory neuropathy. Brain 119:741–753.
Stueve MP, O’Rourke C. (2003) Estimation of hearing
loss in children: comparison of auditory steady-state
response, auditory brainstem response, and behavioral
test methods. Am J Audiol 12:125–136.
Swanepoel D, Hugo R, Roode R. (2004) Auditory
steady-state response for children with severe to
profound hearing loss. Arch Otol Head Neck Surg
130:531–535.
Vander Werff KR, Brown CJ, Gienapp BA, Schmidt
Clay KM. (2002) Comparison of auditory steady-state
response and auditory brainstem response thresholds
in children. J Am Acad Audiol 13:227–235.
Yoshinaga-Itano C, Sedley AL, Coulter DK, Mehl AL.
(1998) Language of early- and later-identified children
with hearing loss. Pediatrics 102:1161–1171.
300