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W Jesteadt

Publications and source records attributed to W Jesteadt.

At least 19 recordsLinked to original sources
PubMed1992

Two experiments on the spectral boundary conditions for nonlinear additivity of simultaneous masking.

The present paper describes the results from two experiments which explored the spectral boundaries for the nonlinear additivity of simultaneous masking. The first experiment measured the threshold for detection of a 2-kHz tone in the presence of two 800-Hz-wide bands of noise that had varying degrees of spectral overlap with each other and the 2-kHz signal. Results revealed an abrupt transition from linear to nonlinear additivity of masking as the spectral separation between the two maskers varied from some overlap to none. The second experiment examined alternative explanations for the data. Explanations based on restricted-listening or distortion-product-detection hypotheses were not supported by the results of this experiment. These data indicate that nonlinear additivity of simultaneous masking holds for maskers that do not overlap within the critical band centered on the signal frequency. This interpretation is also consistent with a large body of data on the monaural and binaural summation (additivity) of loudness.

Adult↗
PubMed1991

Modeling the interactions between noise exposure and other variables.

The interaction of noise exposure with other variables is reviewed. For the case of the interaction of noise with other variables that produce behavioral threshold shifts, the application of a newly developed model is described and demonstrated. This model, referred to as the modified power-law model, provides an accurate prediction of the combined effects of two threshold-elevating factors. The model accounts for the interaction of post-exposure a pre-existing pre-existing permanent loss or a pre-existing temporary loss. The model's application is demonstrated for multiple exposures to steady-state noise in which each exposure lasts as short as 12 min or as long as 6 h. Finally, implications of the model's application to the interaction long as 6 h. Finally, implications of the model's application to the interaction of noise with other ototraumatic agents are reviewed.

Auditory Fatigue↗
PubMed1991

Models of the effects of threshold on loudness growth and summation.

The present paper extends previous efforts to compare models of additivity of masking in normal and impaired listeners to measures of loudness. A model that provides a good account of additivity of masking for normal and impaired listeners, the modified power-law model with compressed internal noise, also provides a good description of basic loudness data from normal and impaired listeners. This model has been discussed frequently in the literature on loudness as one means of correcting loudness functions near threshold, but has not been widely accepted. The applicability of this model to loudness growth and the summation of loudness, both monaurally and binaurally, is evaluated and compared to the more generally accepted alternative. The ability of the model reported here to account for growth of loudness near threshold, as well as the additivity of masking, suggests a need to reconsider its application to loudness data, as well as a need to reconsider the relation between loudness and masking.

Attention↗
PubMed1990

Speech perception in low-pass filtered noise for normal and hearing-impaired listeners.

Two experiments were conducted concerning speech perception in noise. In Experiment 1, a comparison was made between adaptive and fixed-level procedures to estimate the S/N ratio at which 50% correct performance occurred for nonsense syllables for normal-hearing listeners. The two methods yield similar S/N ratio estimates, but the consonant confusions found with the fixed-level method could not be predicted accurately from the adaptive procedure. In Experiment 2, the adaptive procedure was used to estimate the S/N ratio for a 50% performance level in low-pass filtered noise with a range of cutoff frequencies. Data were obtained from 5 normal-hearing listeners at two speech levels (50 and 75 dB SPL) and 4 hearing-impaired listeners at one speech level (75 dB SPL). The hearing-impaired listeners required a better S/N ratio than the normal listeners at either presentation level for all except the widest bandwidth, where their S/N ratios began to converge with the normal values. In addition, the S/N ratios for the hearing-impaired listeners plateaued at relatively narrow bandwidths (0.75 to 2.5 kHz) compared to the normal-hearing group (3.0 to 5.0 kHz). That is, the addition of high-frequency components to the noise did not alter performance. These findings suggest that the hearing-impaired listeners may have relied upon either low-frequency cues or prosodic cues in the perception of these test items.

Adaptation, Physiological↗
PubMed1989

Auditory brainstem responses from children three months to three years of age: normal patterns of response. II.

Auditory brainstem responses (ABR) were measured in 535 children from 3 months to 3 years of age. The latencies reported in this paper should be unaffected by peripheral hearing loss because each child had bilateral wave V responses at 20 dB HLn. Wave V latencies decreased as age increased, at least to 18 months of age, while little or no change was noted in wave I latencies over the same age range. Thus, interpeak latency differences followed the same developmental time course as wave V. The shapes of wave V latency-level functions were comparable across age groups. These results suggest that changes in wave V latency with age are due to central (neural) factors and that age-appropriate norms should be used in evaluations of ABR latencies in children. Interaural differences in absolute wave V latencies and interpeak latency differences were similar to those observed in infants and adults, indicating that response symmetry is independent of age. Statistical analyses suggested that the distributions of absolute and relative latency measurements are normal, making it possible to describe norms in terms of means and standard deviations. A simple model is described that accounts accurately for changes in mean wave V latencies as function of age from preterm through the first three years of life.

Audiometry, Evoked Response↗
PubMed1989

Models of the additivity of masking.

Three models of masking additivity are reviewed, which are referred to as the high-compression model [M. J. Penner, J. Acoust. Soc. Am. 67, 608-616 (1980); M. J. Penner and R. M. Shiffrin, J. Acoust. Soc. Am. 67, 617-627 (1980)], the power-law model [R. A. Lutfi, J. Acoust. Soc. Am. 73, 262-267 (1983); 80, 422-428 (1986)], and the modified power-law model with compressed internal noise [Humes et al., J. Acoust. Soc. Am. 83, 188-202 (1988)]. While the high-compression model was derived from data for two or more nonsimultaneous maskers and the power-law model was derived from data for two or more simultaneous maskers, the modified power-law model can be applied to both cases. The modified power-law model assumes that the threshold in quiet is equivalent to a masked threshold resulting from an internal noise that is continually present. Additional assumptions concern the interaction of two maskers prior to the addition of the masking effects. Most of the data on the additivity of masking are well described by the modified power-law model, regardless of the nature of the maskers. Thus the model provides a good description of data for combined simultaneous maskers and combined nonsimultaneous maskers, a task heretofore requiring the use of at least two separate and independently developed models.

Auditory Threshold↗
PubMed1989

High-frequency audiometry: test reliability and procedural considerations.

This study compared the reliability of a recently developed high-frequency audiometer (HFA) [Stevens et al., J. Acoust. Soc. Am. 81, 470-484 (1987)] with a less complicated system that uses supraaural earphones (Koss system). The new approach permits calibration on an individual basis, making it possible to express thresholds at high frequencies in dB SPL. Data obtained from 50 normal-hearing subjects, ranging in age from 10-60 years, were used to evaluate the effects on reliability of threshold variance, earpiece/earphone fitting variance, and the variance associated with the HFA calibration process. Without earpiece/earphone replacement, the reliability of thresholds for the two systems is similar. With replacement, the HFA showed poorer reliability than the Koss system above 11 kHz, largely due to errors in estimating the calibration function. HFA reliability is greater for subjects with valid calibration functions over the entire frequency range. When average correction factors are applied to the Koss data in an effort to convert threshold estimates to dB SPL, individual transfer functions are not represented accurately. Thus the benefit of being able to express thresholds at high frequencies in dB SPL must be weighed against the additional source of variability introduced by the HFA calibration process.

Adolescent↗
PubMed1989

Normative thresholds in the 8- to 20-kHz range as a function of age.

Using a prototype high-frequency audiometer, auditory thresholds in the 8- to 20-kHz range were obtained from 240 subjects ranging in age from 10-60 years. These measurements were obtained in interest of developing a normative database for frequencies above 8 kHz, and to evaluate intersubject variability as a function of age. An analysis of variance (ANOVA) revealed significant effects of frequency, age, and sex, and a significant frequency-by-age interaction. The largest changes in sensitivity with age occurred between 40 to 59 years. Below approximately 15 kHz, the intersubject variability of threshold estimates increased as a function of both age and frequency. Further analysis revealed that the age-related changes in variability were related to absolute thresholds rather than to age per se. When data are converted to dB HL (relative to the youngest group tested), the region of maximum hearing loss shifts to lower frequencies with increasing age, and threshold shifts with age are greatest in the 13- to 17-kHz range.

Adolescent↗
PubMed1988

Auditory brainstem responses to tone bursts in normally hearing subjects.

Auditory brainstem responses were recorded from 20 normally hearing subjects using tone-burst stimuli that were gated with cosine-squared functions. Clear responses were observed over a wide range of frequencies and levels. These responses were highly reproducible within individual subjects and were reliably measured by two independent examiners. ABR thresholds were higher than behavioral thresholds for all frequencies, especially for lower frequencies. Intersubject variability also was greater for lower frequencies. Wave-V latencies decreased with increases in both frequency and level for frequencies from 250 to 8000 Hz and for levels from 20 to 100 dB SPL. The standard deviations seldom exceeded 10% of the mean wave-V latency for any combination of level and frequency. These latencies can be viewed as the sum of both a peripheral and a central component. Assuming that the central component is relatively independent of both frequency and level, changes of wave V latency must be related to peripheral factors, such as travel time along the cochlear partition, and to stimulus characteristics, such as rise time.

Acoustic Stimulation↗
PubMed1988

The reliability of auditory thresholds in the 8- to 20-kHz range using a prototype audiometer.

This study was designed to evaluate both intra- and intertester reliability of auditory thresholds in the 8- to 20-kHz range using a recently developed high-frequency audiometer [Stevens et al., J. Acoust. Soc. Am. 81, 470-484 (1987)]. With this device, signals from a high-frequency transducer are introduced into the ear canal via a plastic tube. A calibration function is calculated for each ear and used to estimate the sound-pressure level (SPL) at the tympanic membrane. Twenty normal-hearing listeners were tested four times, twice by each of two examiners. In the higher frequencies, accurate calibration functions could not be obtained for many subjects; in these cases, values extrapolated from lower frequencies were used to estimate SPL. Findings reveal that the standard error of measurement for both intra- and intertester measures increases as a function of frequency. Intertester variability was only slightly higher than intratester variability. In most cases, variability of threshold estimates in dB SPL was higher than that observed for the uncorrected attenuator settings. Exclusion of extrapolated values improved reliability substantially.

Adult↗
PubMed1988

Latency of auditory brain-stem responses and otoacoustic emissions using tone-burst stimuli.

A comparison of the latency of auditory brain-stem responses (ABR) and evoked otoacoustic emissions (EOAE) has led to an interpretation for the travel of transients in the peripheral auditory system that is consistent with both sets of data. The "cochlear echo" theory for the origin of the EOAE indicates that the latency of a particular frequency component back to the ear canal should be twice the forward latency of its characteristic place in the cochlea. The latency of wave V of the ABR to tone-burst stimuli can be described as the sum of two components: (1) a component that varies with intensity and frequency in an orderly and predictable manner and (2) a component that is independent of both intensity and frequency. Because the EOAE data can be predicted by taking twice the value of component (1) of the ABR latency, this component is interpreted to be due to mechanical travel through the cochlea. A consequence of this interpretation is that the remaining neural component of the ABR latency must be relatively independent of frequency and intensity.

Acoustic Stimulation↗
PubMed1987

Auditory brainstem responses from graduates of an intensive care nursery: normal patterns of response.

Auditory brainstem responses (ABR) were obtained from graduates of an intensive care nursery (ICN) when those babies were in stable physiological states and ready for hospital discharge. Intensity ranged from ABR threshold to 80 dB nHL, and all recordings were made in a sound-isolated chamber. The data reviewed here are from 585 babies having presumably normal hearing, based upon bilateral ABR thresholds of 30 dB nHL or less. To insure that estimates of population statistics were not biased by high correlations between ears, only the data from the left ears were used in most analyses. Larger correlations were observed between conceptional age (CA) and ABR latencies than between either gestational age (GA) or chronological age (CHA) and the same latencies. Data were grouped into six CA groups for further analyses. Distributions of all response-component latencies were similar in shape and depended upon CA, showing orderly decreases in latency with increasing age. None of these distributions differed significantly from normal, and they were well fitted by normal ogives. Thus, accurate estimates of percentiles can be obtained from the means and standard deviations. The results indicate that it is important to take CA into account when evaluating ABR latencies.

Audiometry, Evoked Response↗
PubMed1987

Growth of masking as a measure of response growth in hearing-impaired listeners.

Growth-of-masking functions were obtained from 19 normal and 5 hearing-impaired listeners using a simultaneous-masking paradigm. When masker and probe frequency are identical, the slope of masking approximates 1.0 for both normal-hearing and impaired listeners. For masker frequencies less than or greater than probe frequency, the slopes for impaired listeners are shallower than those of normals. These findings are consistent with previously reported physiological data (single-fiber rate versus level and AP masking functions) for animals with induced cochlear lesions. Results are discussed in terms of a potential masking technique to estimate the growth of response in normal and impaired ears.

Adolescent↗
PubMed1987

Effects of pure-tone forward masker duration on psychophysical measures of frequency selectivity.

The effects of forward masker duration on psychophysical measures of frequency selectivity were investigated in two experiments. In both experiments, masker duration was 50 or 400 ms, signal duration was 20 ms, and there was no delay between masker offset and signal onset. In the first experiment, growth-of-masking functions were measured for a masker whose frequency was below, at, or above the 1000-Hz signal frequency. From those data, input filter patterns (IFPs) were plotted for masker levels from 40-90 dB SPL. In the second experiment, masking patterns (MPs) were measured for a 1000-Hz masker presented at 50, 70, and 90 dB SPL. Both measures of frequency selectivity (IFPs and MPs) indicate that frequency selectivity is greater for the 400-ms masker. These data suggest that there may be a sharpening of frequency selectivity with time at a stage prior to the adaptation observed in forward masking.

Adult↗
PubMed1985

The role of suppression in psychophysical measures of frequency selectivity.

The neural output of the cochlea consists of a structured spectral representation of the input waveform. Psychophysical studies of frequency selectivity provide measures of the quality of this spectral representation based on the detection of a spectrally narrow signal in the presence of competing acoustic inputs. Results are often interpreted in terms of the underlying physiological processes. The present paper begins with a summary of the basic principles and data and a review of recent efforts to extend the theoretical framework to account for a wider range of phenomena. It then discusses and evaluates specific assumptions concerning the role of suppression in psychophysical measures of frequency selectivity, an area of research that has received much attention in recent years. The goal is to provide a summary of current answers to basic questions at a time of rapidly expanding knowledge about both the physiology and psychophysics of frequency selectivity.

Animals↗
PubMed1977

Sequential effects in judgments of loudness.

A multiple regression analysis of sequential effects in magnitude estimation and absolute identification is presented as an alternative to the approach used by Lockhead and his students. The new analysis indicates that sequential effects do not extend over more than one trial. This is in agreement with the response ratio hypothesis. A more detailed multiple regression analysis of these sequential effects indicates that the magnitude of the correlation between successive responses is heavily dependent on the decibel difference between successive signals. This is not in agreement with the response ratio hypothesis, and the hypothesis is reformulated to take account of this finding. This modification of the model is tested by comparing distributions of normalized responses to theoretical distributions suggested by the model and to a possible alternative distribution.

Acoustic Stimulation↗