University Communications Sciences and Disorders
effects of transient-noise reduction algorithms on speech
intelligibility and user ratings among hearing-impaired users. American
Journal of Audiology 20, 140-150.
J. DiGiovanni, Erin A. Davlin, & Naveen K. Nagaraj
Goal of the study was to asses the functional utility of transient
noise reduction (TNR) algorithms available in hearing aids via speech
intelligibility ans user preferences. Two different pairs of hearing
aids were programmed for a group of individuals with hearing
impairment. Intelligibility was then measured for each participant in a
variety of different conditions. Each condition was tested with TNR
activated and TNR deactivated in a counterbalanced, single-blinded
format. Subjective ratings of overall speech understanding were
obtained from participants after each condition. The results found a
significant improvement in speech intelligibility with TNR activated
when listeners were presented with multitalker babble, in the presence
of chair clang transient noise, and when combining these noises.
Activation of the TNR algorithm did not result in significant
improvements from any other subjective ratings. TNR appears to offer an
incremental step in improving listening experience for heating aid
of in situ thresholds and integrated real-ear measurements. (2010).
Journal of the American Academy of Audiology 21, 663-670.
prescriptive gain results in a more accurate fit, lower return rate in
hearing aids, and increased patient satisfaction. In situ threshold
measurements can be used to determine required gain. The Widex
Corporation uses an in situ threshold measurement strategy, called the
Sensogram. Real-ear measurements determine if prescriptive gain targets
have been achieved. Starkey Laboratories introduced an integrated
real-ear measurement system in their hearing aids. The purpose of this
article was to determine whether the responses obtained using the Widex
Sensogram were equivalent to those obtained using current clinical
threshold measurement methods. To determine the accuracy of the Starkey
IREMS™ (Integrated Real Ear Measurement System) in measuring RECD
(real-ear to coupler difference) values compared to a dedicated
real-ear measurement system. A significant difference between Sensogram
thresholds and conventional audiometric thresholds was found with the
Sensogram method resulting in better threshold values at 0.5, 1.0, and
2.0 kHz for both groups. In Experiment 2, a significant difference
between RECD values obtained by the Starkey IREMS and the Audioscan
Verifit system was found with significant differences in RECD values
found at 0.25, 0.5, 0.75, 1.5, 2.0, and 6.0 kHz. The Sensogram data
differ significantly from traditional audiometry at several frequencies
important for speech intelligibility. Real-ear measures are still
required for verification of prescribed gain, however, calling into
question any claims of shortened fitting time. The Starkey IREMS does
perform real-ear measurements that vary significantly from benchmark
equipment. These technologies represent a positive direction in
prescribing accurate gain during hearing-aid fittings, but a
stand-alone system is still the preferred method for real-ear
measurements in hearing-aid fittings.
J.J., & Pratt, R.M.
relative contribution of adaptation and temporal integration in forward
masking. (2010). Proceedings of Meetings on
N.K., DiGiovanni, J.J., & Ries, D.T.
aim of this study was to demonstrate the relative contribution of
adaptation and temporal integration on forward masking. In the first of
two experiments, monaural gap-detection, thresholds were measured for
broad-band noise markers having different levels on either side of the
gap. In the second experiment, subjects matched the gap-duration within
comparison noise markers to be perceptually equal to that of standard
noise markers. Levels of standard noise markers and the first noise
marker level of the comparison stimuli were set constant at 30 dB SL.
Gap-duration matches were performed by decreasing the level of the
second noise marker by 5 dB SL relative to the first noise marker in
the comparison stimuli. The results indicated that gap-detection
thresholds increased with a decrease in level of noise after the gap.
Subjects required longer gaps in the gap-duration matching task with a
decrease in level of the second noise marker. Both results are
consistent with the notion that persistence of excitation is the
dominate perceptual mechanism that results from forward masking.
of phonemically-targeted processing in conjunction with compression
processing with spectral enhancement. (2010). Proceedings
of Meetings on Acoustics 9(1), 5-1 – 5-6
DiGiovanni, J.J., Rutledge,
J.C., Umble, C.S., & Mester, A.P.
goal of the present study is to test, individually and in combination,
two signal-processing strategies designed to improve both consonant and
vowel perception. In the first strategy, specific consonants were
targeted for processing to increase amplitude and duration. For
consonants with a duration increase, the adjacent vowel was decreased
proportionately in order to maintain overall word and sentence
duration. Second, Coliga, an adaptive compression-processing strategy
incorporating spectral enhancement, was used to process stimuli.
Hearing-in-noise-test sentences were presented monaurally to
normal-hearing and hearing-impaired adults in the presence of
speech-shaped noise. For normal-hearing listeners, it appears that
Coliga is improving intelligibility in certain conditions. Conservative
amounts of duration and amplitude processing need to be applied in
combination rather than when applied independently in order to provide
benefit. For the hearing-impaired listeners, Coliga with spectral
enhancement resulted in poorer performance than without, for all
conditions except for the Coliga-only conditions, where the
intelligibility was the same. It appears that phonemically- targeted
speech processing and Coliga are working antagonistically due to either
1) the processing method negating the benefits when the two are
combined, or 2) combining the duration and amplitude components leading
to no benefit despite documented benefit of each when employed
of recurrent tonal information on auditory working memory for pitch.
(2009). Hearing Research 255, 14-21.
Ries, D.R., & DiGiovanni,
study ascertained the influence of repeating pitch information within
an intervening tonal sequence upon the extent of interference for a
pitch standard held within auditory working memory as measured by the
difference limen for frequency (DLF). Standard and comparison tones
were presented to subjects and same/different responses were obtained
using a touch screen monitor and the DLF was measured using single
interval adjustment matrix (SIAM) procedure [Kaernbach, C., 1990. A
single-interval adjustment-matrix (SIAM) procedure for unbiased
adaptive testing. J. Acoust. Soc. Am. 88, 2645-2655]. Estimates of the
DLF were obtained in a control condition with a silent inter-comparison
interval and three conditions containing intervening tones within the
temporal gap between the standard and comparison stimuli. The presence
of intervening stimuli produced a significant increase in the DLF when
the intervening tonal sequence contained tones with pitches that
differed from that of the standard (Int condition) as well as when the
sequence contained a tone with a pitch identical to that of the
comparison (RptCmp condition). Further, the DLFs obtained for RptCmp
condition were significantly higher than those measured in the Int
condition. The DLFs measured in the condition where the pitch of an
intervening tone was identical to the standard were significantly lower
than those for the Int and RptCmp condition, but did not differ from
the DLFs for the control condition. These results indicate that either
a release from or an increase in interference in auditory working
memory for pitch can occur dependent upon the frequency relationships
between of the standard, comparison, and intervening tones.
role of temporal-masking patterns in the determination of subjective
duration and loudness for ramped and damped sounds. (2008). Journal
of the Acoustical Society of America, 124 (6).
D.R., Schlauch, R.S., & DiGiovanni, J.J.
association between temporal-masking patterns, duration, and loudness
for broadband noises with ramped and damped envelopes was examined.
Duration and loudness matches between the ramped and damped sounds
differed significantly. Listeners perceived the ramped stimuli to be
longer and louder that the damped stimuli, but the outcome was biased
by the stimulus context. Next, temporal-masking patterns were measured
for ramped- and damped-broadband noises using three (0.5, 1.5, and 4.0
kHz) 10 ms probe tones presented individually at various temporal
delays. Predictions of subjective duration derived form masking results
underpredicted the matching results. Loudness estimates derived from
models that assume persistence of neural activity after stimulus offset
[Glasberg B.R., and Moore, B. C. J. (2002). “A model of loudness
applicable to time-varying sounds.” J. Audio. Eng. Soc. 50, 331-341;
Chalupper, J., and Fastl, H. (2002) “Dynamic loudness model (DLM) for
normal and hearing-impaired listeners,” Acust. Acta Acust. 88, 378-386]
were greater for ramped sounds than for damped sounds and were close to
the average results obtained via the matching task. Differences in
simultaneous-masked thresholds for these stimuli could not account for
the loudness-matching results. Decay suppression of the later occurring
portion of the damped stimulus may account for the differences in
perception due to the stimulus context; however, a parsimonious
implementation of this process that accounts for both subjective
duration and loudness judgments remains unclear. © 2008
Acoustical Scociety of America.
|The role of consonant duration
and amplitude processing on speech intelligibility in noise.(2008).
Proceedings of Meetings on Acoustics, 4, 050004.
DiGiovanni, J.J., & Stover, A.K.
loss can have drastic effects on communication abilities leading
researchers to strive to find solutions for the associated problems.
Clear speech has been studied in the past as a possible avenue for
improving speech understanding in those with hearing loss. In the
present study, two characteristics of clear speech, increased consonant
duration and consonant amplification, were applied to Hearing-in Noise
Test sentences. Stimuli were presented in sound field to
hearing-impaired and normal-hearing individuals in the presence of
speech-shaped noise, and percentage correct was measured. For HINT
sentence presentations, both groups showed improvements for both
amplitude processing and the 15-ms condition for duration processing.
Results show that increasing consonant duration and amplitude is a
viable approach to improving speech understanding; nevertheless, this
data suggest that there is a significant cutoff point where lengthening
the duration of a consonant can result in a degraded speech signal
from interference in auditory working memory for pitch. (2007).
Hearing Research, 230, 64-72.
Ries, D.T., & DiGiovanni,
purpose of this study was to quantify the effect of interpolated tones
upon a pitch standard held within auditory working memory through
measurement of the difference limen (just noticeable difference) for
frequency and the usefulness of “Where” cues to ameliorate the
interference produced by these intervening stimuli. To this end, we
measured the degree to which tones, containing identical and disparate
localization cues, presented within the retention interval altered
differential sensitivity for frequency via the method of constant
stimuli. The difference limen for frequency nearly tripled when tones
were presented within the retention interval and sound localization
cues produced a significant partial release from interference within
the short-term pitch store. Interference produced by “Where” cues
ranged from 4.0 to 5.2 Hz. These findings indicate that there
possible integrative use of the “What” and “Where” pathways in forming
and maintaining pitch information within the pitch array within
auditory working memory. © 2007 Elsevier B.V. All rights
reflex and ears with high static acoustic admittance. (2007). American
Journal of Audiology, 16, 68-74.
DiGiovanni, J.J., & Ries,
Purpose: To evaluate modified
acoustic reflex diagnostic protocols for a group of individuals (n
= 9) with high peak compensated static acoustic admittance (Ytm)
tympanograms. Method: A modified procedure designed to improve acoustic
stapedius reflex threshold (ASRT) measurements in individuals with
high-admittance tympanograms was employed in both an experimental and a
control group. ASRTs were measured at 0.5, 1.0, and 2.0 kHz,
ipsilateral and contralateral. Measurements were obtained within each
condition for 7 ear canal pressures that were set to 0, ±50, ±100, and
±150 daPa (relative to tympanometric peak pressure [TPP]). Results:
Though measuring ASRTs at –50 daPa (relative to TPP) in the
high-admittance and normal groups did not result in significantly
better thresholds than at TPP, the absent reflex rate was reduced when
the ear canal pressure was changed by –50 daPa during ASRT
measurements. Conclusions: Based on this sample, it is suggested that a
patient presenting with high peak compensated static acoustic
admittance (peak Ytm ≥ 2.1
mmho) undergo ASRT evaluation with the ear canal pressure set to –50
daPa (relative to TPP).
responsible for differences in perceived duration for rising-intensity
and falling-intensity sounds. (2007). Ecological Psychology,
that are equivalent in all aspects except for their temporal envelope
are perceived differently. Sounds with rising temporal
are perceived as louder, longer, and show a greater change in loudness
throughout their duration than sounds with falling temporal
envelopes. Stecker & Hafter (2000) proposed that
ignore the decay portion of sounds with falling temporal envelopes to
account for observed loudness differences, but there is no empirical
evidence support this hypothesis. To test this idea, two
duration-matching experiments were performed. One experiment used
broadband noise and the other natural stimuli. Different
of participants were given different instruction sets asking them to 1)
simply match the duration or 2) include all aspects of the sounds. Both
experiments produced the same result. The first instruction set, which
represented participants’ natural biases, yielded shorter subjective
durations for sounds with falling temporal envelopes than for sounds
with rising temporal envelopes. By contrast, asking
to include all aspects of the sounds significantly reduced the size of
the asymmetry in subjective duration, a result that supports Stecker
and Hafter’s (2000) hypothesis. This segregation of the stimulus at the
perceptual level is consistent with observed asymmetries in loudness
change and overall loudness for sounds with rising and falling temporal
envelopes, but it does not account for the entire effect. The remaining
portion of the effect, after considering biases due to instructions, is
not likely a result of adaptation but could be associated with
persistence. The amount of persistence was inferred from
behavioral masking data obtained for these sounds.
method in manual audiometry for adults. (2007). American
Journal of Audiology, 16, 1-4.
DiGiovanni, J.J., & Repka,
This study compared the speed, false-alarm rate, and participant
preference of different response methods (rasing a hand, pushing a
response button, and giving an oral respose) for measuring pure tone
threshold. Method: Thirty female university students with normal
hearing participated. Response method order was randomly assigned to 6
different groups. Air-conduction thresholds were measured twice for
each response method for each participant in octave intervals between
250 Hz and 8000 Hz. The 2nd threshold measurements were performed on a
different day but within 2 weeks of the initial measurement. Results: A
significant difference was found when comparing the amount of time
necessary to complete the test for each response method. On average, it
took about 1 min less when using the push-button response than when
using hand-raise or verbal response methods. There was also a
significant participant preference for using the response button. No
significant difference between response method for threshold level and
number of false positives was found. Conclusion: This study supports
the use of the response button when measuring auditory threshold for
young adults with normal hearing.
|Response growth using a
low-frequency suppressor. (2007). Hearing
Research, 234 15-20.
DiGiovanni, J.J., & Nair,
psychophysical studies on two-tone suppression have been carried out.
recently, researchers have attempted to relate the magnitude of
the level of suppressee. [Wojtczak, M., Viemeister, N.F., 2005.
response growth under suppression. In: Pressnitzer, D., de Cheveigne,
McAdams, S., Collet, L. (Eds.), Auditory Signal Processing: Physiology,
Psychoaccoustics, and Models. Springer, New York, pp. 67–74]
the magnitude of suppression for a higher-frequency, fixed-level
decreases with increasing level of the suppressee. This suggests a
linearization of the basilar membrane response in presence of a
suppressor. The present study expands these results to a low-frequency
suppressor of varying intensity levels. Detection of a 10-ms, 4.0-kHz
measured under different forward-masking conditions: one with a 200-ms,
masker (suppressee) presented with no suppressor and another with the
masker paired with a 2.2-kHz, 200-ms suppressor. The 4.0-kHz masker
varied adaptively and a range of probe levels was used to measure the
suppression. Results indicate that (1) the magnitude of suppression
with increasing suppressor level and (2) generally, the probe level was
related to the magnitude of suppression. © Elsevier B.V. All rights
filters and the benefit measured from spectral enhancement. (2006). Journal
of the Acoustical Society of America 120, 1529-1538.
DiGiovanni, J.J., & Nair,
designed to improve speech intelligibility for those with sensorineural
hearing loss (SNHL) by enhancing peaks in a spectrum have had limited
success. Since testing of such algorithms cannot separate the theory of
the design from the implementation itself, the contribution of each of
these potentially limiting factors is not clear. Therefore,
psychophysical paradigms were used to test subjects with either normal
hearing or SNHL in detection tasks using well controlled stimuli to
predict and assess the limits in performance gain from a spectrally
enhancing algorithm. A group of normal-hearing (NH) and
hearing-impaired (HI) subjects listened in two experiments: auditory
filter measurements and detection of incremented harmonics in a
harmonic spectrum. The results show that NH and HI subjects have an
improved ability to detect incremented harmonics when there are
spectral decrements surrounding the increment. Various decrement widths
and depths were compared against subjects' equivalent rectangular
bandwidths (ERBs). NH subjects effectively used the available energy
cue in their auditory filters. Some HI subjects, while showing
significant improvements, underutilized the energy reduction in their
auditory filters. ©2006 Acoustical Society of America.
recovery of sudden sensorineural hearing loss: Possible association
with autoimmune disorders. (2006). Journal of the American
Academy of Audiology 27, 498-505.
J.J., & Nair,
46-year-old white male diagnosed with systemic lupus erythematosus
(SLE) and antiphospholipid syndrome (APS) was seen for audiological
testing 15 minutes following a sudden onset hearing loss in the right
ear. The test battery included pure-tone audiometry, word-recognition
testing, speech-recognition threshold (SRT) testing, immittance
testing, and distortion-product otoacoustic emissions (DPOAE) testing.
Testing revealed a sensorineural hearing loss in the right ear. Shortly
after testing, the patient indicated that his condition had improved.
Testing was repeated, and the second round of tests revealed normal
hearing in both ears. Four days later, a follow-up test again indicated
normal hearing in both ears. Possible connections of this brief
occurrence of idiopathic hearing loss with the patient’s medical
conditions are discussed. Specifically, symptoms were consistent with a
transient ischemic attack (TIA) affecting his right cochlea in the
stria vascularis region, resulting in a temporary,sensorineural hearing
loss. No residual effects were observed clinically.
psychophysical evaluation of spectral enhancement. (2005). Journal
of Speech-Language Hearing Research 48(5), 1121-1135
J.J., Nelson, P.B.,
& Schlauch, R.S.
with sensorineural hearing loss have well-documented elevated hearing
thresholds; reduced auditory dynamic ranges; and reduced spectral (or
frequency) resolution that may reduce speech intelligibility,
especially in the presence of competing sounds. Amplification and
amplitude compression partially compensate for elevated thresholds and
reduced dynamic ranges but do not remediate the loss in spectral
resolution. Spectral-enhancement processing algorithms have been
developed that putatively compensate for decreased spectral resolution
by increasing the spectral contrast, or the peak-to-trough ratio, of
the speech spectrum. Several implementations have been proposed, with
mixed success. It is unclear whether the lack of strong success was due
to specific implementation parameters or whether the concept of
spectral enhancement is fundamentally flawed. The goal of this study
was to resolve this ambiguity by testing the effects of spectral
enhancement on detection and discrimination of simple, well-defined
signals. To that end, groups of normal-hearing (NH) and
hearing-impaired (HI) participants listened in 2 psychophysical
experiments, including detection and frequency discrimination of
narrowband noise signals in the presence of broadband noise. The NH and
HI listeners showed an improved ability to detect and discriminate
narrowband increments when there were spectral decrements (notches)
surrounding the narrowband signals. Spectral enhancements restored
increment detection thresholds to within the normal range when both
energy and spectral-profile cues were available to listeners. When only
spectral-profile cues were available for frequency discrimination
tasks, performance improved for HI listeners, but not all HI listeners
reached normal levels of discrimination. These results suggest that
listeners are able to take advantage of the local improvement in
signal-to-noise ratio provided by the spectral decrements.
discrimination and subjective duration of ramped and damped sounds.
(2001) Journal of the Acoustical Society of America, 109, 1880-7.
perception of stimuli with ramped envelopes (gradual attack and abrupt
decay) and damped envelopes (abrupt attack and gradual decay) was
studied in subjective and objective tasks. Magnitude estimation (ME) of
perceived duration was measured for broadband noise, 1.0-kHz, and
8.0-kHz tones for durations between 10 and 200 ms. Damped sounds were
judged to be shorter than ramped sounds. Matching experiments between
sounds with ramped, damped, and rectangular envelopes also showed that
damped sounds are perceived to be shorter than ramped sounds, and,
additionally, the reason for the effect is a result of the damped sound
being judged shorter than a rectangular-gated sound rather than the
ramped sound being judged longer than a rectangular-gated sound. These
matching studies also demonstrate that the size of the effect is larger
for tones (factor of 2.0) than for broadband noise (factor of 1.5).
There are two plausible explanations for the finding that damped sounds
are judged to be shorter than ramped or rectangular-gated sounds: (1)
the abrupt offset at a high level of the ramped sound (or a
rectangular-gated sound) results in a persistence of perception
(forward masking) that is considered in judgments of the subjective
duration; and (2) listeners may ignore a portion of the decay of a
damped sound because they consider it an "echo" [Stecker and Hafter, J.
Acoust. Soc. Am. 107, 3358–3368 (2000)]. In another experiment,
duration discrimination for broadband noise with ramped, damped, and
rectangular envelopes was studied as a function of duration (10 to 100
ms) to determine if differences in perceived duration are associated
with the size of measured Weber fractions. A forced-choice adaptive
procedure was used. Duration discrimination was poorer for noise with
ramped envelopes than for noise with damped or rectangular envelopes.
This result is inconsistent with differences in perceived duration and
no explanation was readily apparent. ©2001 Acoustical Society
laterality and cueing in forward-masked intensity discrimination.
(1999). Journal of the Acoustical Society of America, 105, 822-828.
Schlauch, R.S., Clement, B.R.,
Ries, D.T., & DiGiovanni, J.J.
intensity discrimination was measured as a function of level in
experiments designed to reveal insights into the mechanism(s)
underlying the midlevel elevation of the Weber fraction. The standard
and maskers were 1.0-kHz tones that were separated by 100 ms.
Performance was measured for listeners with normal hearing using an
adaptive procedure. In experiment 1, intensity discrimination was
measured in the presence of an ipsilateral masker (80 dB SPL), a
contralateral masker (93 dB SPL), and a binaural (dichotic) masker
produced by combining the ipsilateral and contralateral maskers.
Listeners perceived only the contralateral masker in the
binaural-masker condition. The contralateral masker produced a small
midlevel elevation of the Weber fraction. The ipsilateral masker and
the binaural masker produced a large, midlevel elevation of the Weber
fraction. Experiment 2 found that a two-tone masker resulted in a
reduction (improvement) in the Weber fraction for some conditions, but
the midlevel elevation remained for all subjects in this cue-tone
condition. Experiment 3 demonstrated that cross talk could not account
for all of the masking observed with contralateral maskers. Taken
together, the results suggest that a single complex mechanism or
multiple mechanisms may be responsible for the masking seen in these
experiments. On the basis of the cueing results, it is concluded that a
portion of the masking is due to cognitive factors; however, a sensory
mechanism cannot be ruled out for the remaining portion, based on the
results of these experiments. Finally, a small but significant amount
of masking due to contralateral maskers places the mechanism for this
outcome central to the cochlear nucleus. ©1999 Acoustical
Society of America.
nonlinearity and loudness. (1998). Journal of the Acoustical
Society of America, 103, 2010-2020.
R.S., DiGiovanni, J.J., & Ries, D.T.
matching functions for tones for persons with one shifted-threshold ear
(hearing loss and noise-shifted thresholds) and one ear within normal
limits were used to derive the presumed basilar membrane (BM)
input–output (I/O) function in a normal ear. The comparison was made by
assuming that the BM I/O function for the ear with the cochlear
threshold shift has a slope of one (a linearized cochlea). The function
for the normal ear was derived from the loudness matching function
based on this assumption. Comparisons were made for archival basilar
membrane data [M. A. Ruggero, N. C. Rich, A. Recio, S. S. Narayan, and
L. Robles, J. Acoust. Soc. Am. 101, 2151–2163 (1997)] for chinchilla
and archival loudness matches for long-duration tones for persons with
various degrees of cochlear hearing loss [F. Miskolczy-Fodor, J.
Acoust. Soc. Am. 32, 486–492 (1960)]. Comparisons were made also
between BM I/O functions and ones derived from loudness matches for
persons with unilateral hearing loss simulated by broadband noise. The
results show a close resemblance between the basilar membrane I/O
function and the function derived from loudness matches for
long-duration tones, even though the comparison was between human and
chinchilla data. As the degree of threshold shift increases from 40 to
80 dB, the derived BM I/O functions become shallower, with slopes for
losses of 60 dB or more falling in the range of values reported for
physiological data. Additional measures with short-duration tones in
noise show that the slope of the loudness function and the slope of the
derived basilar membrane I/O function are associated with the
behavioral threshold for the tone. The results for long-duration tones
suggest a correspondence between BM displacement and loudness
perception in cases of recruitment, but the relation between the degree
of loss and the amount of BM compression and the relation between
signal duration and compression suggests that other factors, such as
the neural population response, may play a role. ©1998
Acoustical Society of America.
discrimination of ramped and damped tones. (1998). Proceedings
of the International Congress on Acoustics and the Acoustical Society
of America, 2, 885-886. 2aPP31.
Schlauch, R.S., Ries, D.T.,
Elliot, S., & Campbell, S.
discrimination of 1.0-kHz tones that had exponentially ramped or damped
envelopes was measured as a function of duration and level. Standard
levels ranged from near threshold to 90 dB SPL and durations ranged
from 10 to 200 ms. Just-noticeable differences for some subjects were
smaller for damped tones than for ramped tones for the same duration
and level. For these conditions, damped tones showed more temporal
integration than ramped tones. This result is somewhat surprising given
that the subjective duration of ramped tones increased by a factor of
100 for stimuli ranging from 10 to 200 ms, whereas the subjective
duration of damped tones increased by a much smaller factor of 28 over
the same range of durations. Possible physiological and cognitive
explanations for these differences will be discussed. [Work supported
by NIH-NIDCD R29 DC01542.]