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Biomedical subjects

L E Humes

Publications and source records attributed to L E Humes.

At least 19 recordsLinked to original sources
PubMed1992

Reliability of two measures of speech recognition in elderly people.

The revised Speech Perception in Noise (SPIN) test and the Dichotic Sentence Identification (DSI) test have been used to help evaluate speech-recognition capabilities in elderly people. We evaluated the test-retest reliability of these measures for 17 subjects aged 63-82 years. The DSI and revised SPIN tests were administered at 65, 75, and 85 dB SPL, with a total of three presentations at each level. Reliability was assessed using a repeated-measures analysis of variance and 95% critical differences for each test. Results raise serious questions about the use of these tests for diagnostic determinations or assessment of speech-recognition ability in elderly people.

Aged↗
PubMed1992

Some psychometric properties of the Test of Basic Auditory Capabilities (TBAC).

This study examined some psychometric properties of the Test of Basic Auditory Capabilities (TBAC). Two experiments are described that evaluate the psychometric functions and the test-retest reliability of the tests comprising the TBAC. The psychometric functions were established for young listeners with normal hearing and the test-retest reliability was evaluated both with young listeners with normal hearing and elderly listeners with hearing impairment. Results indicate that maximum scores on the TBAC are reached at presentation levels of at least 65-75 dB SPL. In addition, the reliability analyses indicate that the TBAC is a reliable measure for both young listeners with normal hearing and elderly listeners with hearing impairment when at least one practice test is given.

Adult↗
PubMed1992

Evaluation of two clinical versions of the articulation index.

The present study evaluated the predictive accuracy of two clinical versions of the articulation index (AI). AI calculations were made and word recognition scores obtained for normal-hearing young adults and elderly hearing-impaired listeners in quiet and in a noise background. The impaired listeners were also evaluated for both aided and unaided listening conditions, with the aided AI values adjusted by the measured real ear insertion gain for each listener. Results revealed that the two clinical AI procedures yielded virtually identical values, and both were accurate predictors of speech recognition performance for unaided conditions. Aided speech recognition performance was predicted less accurately by both methods, especially when a noise background was present. On the other hand, within a given listener, both AI methods were valid indicators of the relative performance across listening conditions.

Acoustic Stimulation↗
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

Speech identification difficulties of hearing-impaired elderly persons: the contributions of auditory processing deficits.

This study examined the performance of four subject groups on several temporally based measures of auditory processing and several measures of speech identification. The four subjects groups were (a) young normal-hearing adults; (b)-hearing-impaired elderly subjects ranging in age from 65 to 75 years; (c) hearing-impaired elderly adults ranging in age from 76 to 86 years; and (d) young normal-hearing listeners with hearing loss simulated with a spectrally shaped masking noise adjusted to match the actual hearing loss of the two elderly groups. In addition to between-group analyses of performance on the auditory processing and speech identification tasks, correlational and regression analyses within the two groups of elderly hearing-impaired listeners were performed. The results revealed that the threshold elevation accompanying sensorineural hearing loss was the primary factor affecting the speech identification performance of the hearing-impaired elderly subjects both as groups and as individuals. However, significant increases in the proportion of speech identification score variance accounted for were obtained in the elderly subjects by including various measures of auditory processing.

Adult↗
PubMed1991

Recognition of synthetic speech by hearing-impaired elderly listeners.

The Modified Rhyme Test (MRT), recorded using natural speech and two forms of synthetic speech, DECtalk and Votrax, was used to measure both open-set and closed-set speech-recognition performance. Performance of hearing-impaired elderly listeners was compared to two groups of young normal-hearing adults, one listening in quiet, and the other listening in a background of spectrally shaped noise designed to simulate the peripheral hearing loss of the elderly. Votrax synthetic speech yielded significant decrements in speech recognition compared to either natural or DECtalk synthetic speech for all three subject groups. There were no differences in performance between natural speech and DECtalk speech for the elderly hearing-impaired listeners or the young listeners with simulated hearing loss. The normal-hearing young adults listening in quiet out-performed both of the other groups, but there were no differences in performance between the young listeners with simulated hearing loss and the elderly hearing-impaired listeners. When the closed-set identification of synthetic speech was compared to its open-set recognition, the hearing-impaired elderly gained as much from the reduction in stimulus/response uncertainty as the two younger groups. Finally, among the elderly hearing-impaired listeners, speech-recognition performance was correlated negatively with hearing sensitivity, but scores were correlated positively among the different talker conditions. Those listeners with the greatest hearing loss had the most difficulty understanding speech and those having the most trouble understanding natural speech also had the greatest difficulty with synthetic speech.

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↗
PubMed1991

Understanding the speech-understanding problems of the hearing impaired.

This article presents a tutorial overview of the speech-recognition difficulties of the hearing impaired. Much recent research indicates that the primary problem underlying the speech-recognition difficulties of the hearing impaired is the loss of hearing sensitivity and accompanying loudness recruitment. This tutorial demonstrates why loss of hearing sensitivity plays such an important role and why hearing aids fitted with contemporary fitting strategies provide only limited benefit in noise for many of these individuals. In addition, low-pass noise is often said to present the hearing-impaired listener with greater difficulties than broad-band noise. This observation is also explained quite simply by careful consideration of the loss of hearing sensitivity. Finally, two clinical articulation index (AI) calculation schemes, designed to quantify the effects of hearing loss on speech understanding, are reviewed and evaluated.

Audiometry, Speech↗
PubMed1979

Perception of the simple difference tone (f2-f1).

The present study examined the dependence of difference tone level [L(f2-f1)] on the following parameters of the two-tone input: f1, f2/f1 (f2 greater than f1), L1, L2, and L1 = L2. Difference tone levels were estimated in four normal hearers using a 2AFC adaptive temporal gap-masking paradigm. The key finding in this study is the apparent interaction of each factor with the other. For example, primary level (L1 = L2) was found to affect the dependence of L(f2-f1) on f1 and on f2/f1. In addition, the frequency separation of the primaries (f2/f1) was also seen to exert an influence on the dependence of difference tone level on L1, L2, and L1 = L2.

Acoustic Stimulation↗
PubMed1979

Two experiments on subtle mid-frequency hearing loss and its influence on word discrimination in noise-exposed listeners.

The present study consisted of two experiments. Experiment I was directed toward the detection of subtle mid-frequency cochlear dysfunction and the determination of word discrimination in noise for persons with noise-induced hearing loss. The presence of significantly elevated aural-overload thresholds, consistent with the presence of cochlear pathology in regions of normal pure-tone sensitivity, confirmed previous findings obtained with this subject population by other investigators. In addition, a marked reduction in word discrimination was observed in the presence of a background of competing noise. For experiment II, normal hearers listened to consonant-nucleus-consonant monosyllables filtered to match the mean audiometric configuration of the noise-exposed subjects in experiment I. Results showed significantly better performance with these filtered words by the normally hearing subjects than that by the noise-exposed group for unfiltered materials. The results of the second experiment were interpreted as providing further support for the presence of subtle auditory dysfunction in the mid-frequencies despite normal threshold sensitivity in this same frequency region.

Acoustic Stimulation↗
PubMed1979

Performance intensity functions in cochlear and eighth nerve disorders.

In this report, performance intensity functions for monosyllabic materials (PI-PB) were obtained on two groups of subject: 20 patients with eighth nerve pathology and 15 individuals with Meniere's disease. The subjects with retrocochlear involvement exhibited marked deterioration in word recognition as the speech intensity was increased beyond the level required for a maximum discrimination score. Such a dramatic breakdown, referred to as the "rollover effect," was not seen to occur among the subjects with cochlear disorders. Hence, the PI-PB function appears to be a valuable tool for use in the special test battery.

Adolescent↗
PubMed1978

The aural-overload test: twenty years later.

This paper reviews the underlying theory, the psychophysical test procedure, and the clinical applications of the aural-overload test. Clinical applications include (1) the delineation of persons susceptible to acoustic trauma, (2) the evaluation of post-exposure damage to the auditory system, (3) assistance in site-of-lesion testing, and (4) the assessment of loudness recruitment. The relationship between aural-overload thresholds and speech-discrimination scores for normal and pathological ears is also discussed.

Auditory Pathways↗
PubMed1977

Review of four new indices of susceptibility to noise-induced hearing loss.

The potential use of four new measures of susceptibility to acoustic trauma has been discussed. Each has the advantage, unlike TTS methodology, of not requiring a prior exposure stimulus. The use of an exposure sound has proven to be the major drawback to verification of Temkin's original hypothesis. A disadvantage inherent to the speech discrimination procedures involves the use of difficult-to-standardize speech materials and techniques. Consequently, one of the first three techniques, aural overload, threshold of octave masking, and brief-tone audiometry, is more desirable with aural overload having the most data to substantiate its use as a predictor of vulnerability to ear damage from acoustic overstimulation. None of these tests, on the other hand, has been correlated to permanent threshold shift (PTS). This necessitates the use of experimental animals or the long-term monitoring of the hearing sensitivity of industrial workers. Such data should prove invaluable in the search for an effective predictor of eventual noise-induced hearing loss.

Audiometry↗
PubMed1977

Influence of overstimulation on temporary threshold shift and the onset of aural overload.

This investigation sought to examine the sensitivity of pure tone thresholds and the onset of aural overload to the fatiguing effects of broad band noise. Noise levels ranging from 35 to 110 dB SPL were presented to 8 normal hearers. Post-exposure pure tone thresholds were determined for octave frequencies 500-4000 Hz while aural overload thresholds were obtained for the fundamental frequencies of 500 and 2000 Hz. Aural overload thresholds were found to decline following exposure levels insufficient to produce measurable TTS. This was particularly evident for low-frequency stimuli (below 2000 Hz). Results suggested that the aural overload test may be a more effective indication of cochlear damage than is the traditional temporary threshold shift procedure. These findings are discussed in terms of the "injured hair cell" hypothesis proffered by Wever & Lawrence (1955).

Acoustic Stimulation↗
PubMedDate not supplied

A test battery approach to the investigation of susceptibility to temporary threshold shift.

This study examined individual differences among various psychophysical measures that have been suggested previously as predictors of susceptibility to noise-induced temporary threshold shift (TTS). The test battery was administered to a group of five normal-hearing young adults and consisted of the following procedures: (1) critical intensity (CI) at 2 kHz; (2) loudness discomfort level (LDL) at 0.5, 1, 2 and 4 kHz; (3) aural overload thresholds at 0.5, 1 and 2 kHz. Three measures of TTS, one employing a broad-band noise as the exposure stimulus and two others using tonal fatiguers, were utilized to assess susceptibility to TTS. Results revealed that the test battery delineated tough from tender ears. Furthermore, the aural overload test was found to be a highly accurate predictor of TTS.

Acoustic Impedance Tests↗
PubMedDate not supplied

The effects of middle ear muscle contraction on auditory and overload thresholds.

The present investigation examined psychophysically the frequency-specific and nonlinear attenuation of sound energy provided by middle ear muscle contraction in normal hearers. Aural overload and absolute auditory thresholds were measured at 500, 1 000 and 2 000 Hz prior to and during acoustic stapedial reflex contraction. Reflex contraction was elicited with contralateral broad-band noise. Results revealed that overload thresholds were elevated at 500 and 1 000 Hz and a slight decrease in overload threshold was apparent at 2 000 Hz during reflex contraction while absolute thresholds remained essentially unchanged. These data are consistent with previous psychophysical and physiological findings. The aural overload test having been derived directly from observations of cochlear microphonic saturation, moreover, affords direct comparison to results of electrophysiological experimentation.

Acoustic Stimulation↗