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Biomedical subjects

S A Gelfand

Publications and source records attributed to S A Gelfand.

35 records · Page 2Linked to original sources
PubMed1982

Clinical application of the bivariate plotting procedure in the prediction of hearing loss.

This study examined the utility of the bivariate plotting approach to reflex-based hearing loss prediction, and introduced a modification to the method which accounts for the effects of mild and high frequency hearing losses. The effect of pure tone sensitivity at 3,000 Hz was found to be of particular importance in the predictive accuracy of the method. When 3,000 Hz is considered, the original concept of the bivariate graph can be further refined into three regions. Here, normal ears and those with substantial hearing loss can be identified with considerable success. A "grey area" between these correctly identifies some degree of loss with 89% accuracy.

Adult↗
PubMed1981

The relationship between magnitude of hearing loss and acoustic reflex threshold levels.

The acoustic reflex threshold (ART) was studied in 544 ears having hearing levels (ANSI-1969) ranging from 0 to 110 dB HL. The activating signals were pure tones (500, 1000, and 2000 Hz) presented at levels up to 125 dB HL. The results indicated that the ART increased with hearing loss beyond certain levels. The proportion of absence of reflex responses depends upon the degree of hearing loss, test frequency, and the limits imposed by the instrumentation. Absence of reflex responses is rare for hearing losses of less than about 80 dB HL when the hearing loss is attributable to cochlear involvement.

Acoustic Impedance Tests↗
PubMed1981

Acoustic reflex thresholds in young and elderly subjects with normal hearing.

This study replicated Silman's [J. Acoust. Soc. Am. 66 (1979a)] experiment comparing acoustic reflex thresholds in normal hearing young and elderly subjects. The original study was modified so that the criterion for normal hearing was extended through 8000 Hz, and the range of auditory thresholds among the younger group was selected to approximate those of the elderly subjects as closely as possible. The data confirmed those reported by Silman, showing an elevation of the ART for broadband noise, but nor for tonal activators in the elderly group.

Adult↗
PubMed1981

Effect of sensorineural hearing loss on the stapedius reflex growth function in the elderly.

The effect of sensorineural hearing loss upon stapedius reflex growth functions was studied in the elderly. The reflex activators were pure tones (500, 1000, and 2000 Hz) and broadband noise; reflex magnitude was expressed in decibels relative to static acoustic impedance. When expressed in decibels relative to reflex threshold, the mean growth functions of the elderly were reduced compared to previous data for young subjects [Silman, Popelka, and Gelfand, J. Acoust. Soc. Am. 64, 1406--1411 (1978)] and the noise functions differed in terms of both shape and magnitude. When expressed in SPL, the mean growth functions of the normal hearing elderly demonstrated saturation at high activator levels, whereas saturation was not observed in the mean growth functions of the hearing loss subjects. In the normal elderly, saturation was found to be frequency dependent. The saturation effect is discussed in terms of energy integration of the reflex response in the aging ear.

Acoustic Stimulation↗
PubMed1980

Dichotic CV recognition at various interaural temporal onset asynchronies: effect of age.

Dichotic CV recognition at interaural temporal onset asynchronies (lag times) of 0, 30, 60, and 90 ms was investigated in normal hearing young and elderly subjects. The results for the young group were consistent with those reported in previous studies (Studdert-Kennedy et al., 1970; Berlin et al., 1973a). The older group demonstrated a mean right ear advantage (REA) at simultaneity of 12.7%, which was not significantly different from that of the young group (12.4%). This suggests that the processes subserving the REA are not affected by age. However, there was a significant reduction in the total (right ear plus left ear) dichotic scores of the elderly group compared to the young; suggesting an age-associated reduction in the channel capacity of the aging auditory system. Further, there were striking aberrations of the dictotic lag effect in the elderly group compared to the young subjects, consistent with age-related changes in auditory temporal processing. The findings are discussed with respect to the aging auditory system and the nature of dichotic speech processing.

Adolescent↗
PubMed1979

Usage of CROS hearing aids by unilaterally deaf patients.

Fifty (58%) unilaterally deaf patients responded to a contralateral routing of signals (CROS) hearing aid usage questionnaire. Their actual usage in communicative environments was quite variable, with 50% to 60% of the time being the avarage in most of these situations. Mean communicative usage was essentially similar when the ambient nature of the environment could be described as quiet, speech competition, noise and/or speech babble, and reverberant/noisy. It is extremely difficult to determine who will be a successful CROS wearer on the basis of diagnostic results that are obtained with the use of earphones. Not every unilateral listener is a CROS candidate. The importance of a sound-field evaluation in a controlled environment, a trial period, and follow-up consultations cannot be overemphasized.

Adult↗
PubMed1979

Prediction of hearing levels from acoustic reflex thresholds in persons with high-frequency hearing losses.

This study examined the precision of the bivariate method in subjects with high-frequency sensorineural hearing loss. The current bivariate data effectively separated normal hearing subjects from those with pure tone averages of greater than 32 dB HL, in a manner consistent with the results of Popelka and Trumpf (1976) and Margolis and Fox (1977b). However, for persons with high-frequency losses the prediction of hearing levels from acoustic reflex thresholds (ARTs) appears to be complicated. Moderate hearing losses involving 500, 1000 and 2000 Hz ("speech frequencies") as well as higher frequencies were identified on the basis of elevated average ARTs for 500, 1000 and 2000 Hz. Normal ears (pure tone averages of less than 30 dB HL) were isolated from others on the basis of position on the bivariate graph. Those with (1) normal hearing in the "speech frequencies" and a high-frequency loss and (2) a mild loss in the "speech frequencies" and a high-frequency loss, could be separated from those with normal hearing by location on the bivariate graph, and from those with moderate (or worse) losses on the basis of average ART for tones. Consideration of these findings is useful in the evaluation of patients at risk for high-frequency loss, such as patients with noise exposure, and is particularly useful in cases of suspected functional impairment within this population. A modification of the bivariate method is suggested which extends its application to patient populations with a large incidence of high frequency sensorineural hearing loss.

Adult↗
PubMed1978

Some observations in a case of acoustic neuroma.

The subject was a 47-year-old male with a moderate asymmetrical sensorineural hearing loss that initially presented cochlear signs except for positive stapedius reflex results. Over the course of only five weeks, he developed the audiological constellation of retrocochlear involvement. The retrocochlear results were confirmed by the removal of an acoustic tumour. The results highlight the importance of audiological monitoring and reflex measures in the identification of acoustic neuromas. Several observations provide insight into the apparent relationship between loudness and the stapedius reflex. The findings are discussed with reference to a proposed extension of Borg's recent theory that elevated reflex thresholds and reflex decay reflect differing degrees of the eighth nerve destruction.

Auditory Threshold↗
PubMed1978

Effect of sensorineural hearing loss on acoustic stapedius reflex growth functions.

The growth function of the acoustic stapedius reflex was measured in subjects with normal hearing and sensorineural hearing loss of cochlear origin. The effects of age and magnitude of hearing loss were controlled. Activating stimuli were 500, 1000, and 2000 Hz tones and broadband noise. Stapedius muscle activity was inferred from acoustic impedance measures in the contralateral ear. The mean growth functions for tones were essentially linear in log-log plots with the rate of growth equal for the two groups. The mean growth function for the noise signal was curvilinear for the normal hearing groud had linear for the hearing loss group. Comparison of slope functions derived from the fitted data indicated that the rate of reflex growth for the noise signal, over a limited range above reflex threshold, is greater in ears with cochlear lesions than normal ears. For higher level noise signals, however, the rate of reflex growth is similar for normal and pathological ears. The effect of a cochlear lesion on the input-output function of the cochlea for both tonal and noise stimuli is to maintain the rate of reflex growth but shift the function along the intensity axis of a tonal signal and the response axis for a noise signal.

Acoustic Impedance Tests↗
PubMedDate not supplied

Usage of CROS and IROS hearing aids by patients with bilateral high-frequency hearing loss.

Responses to a hearing aid usage questionnaire were received from 128 patients with high-frequency sensorineural hearing loss fitted monaurally with contralateral routing of signals (CROS) or ipsilateral routing of signals (IROS) hearing aids. Functional benefits were demonstrated by wearing the instruments 8 to 9 hr/day, use of the aids about 60% of the time in communicative situations, subjective benefit judgements of 5 to 9 on a 10-point scale, improved subjective sound localization, and improved clarity of speech with the hearing aids. Although CROS and IROS fittings could not be separated on the basis of these factors, considerably more complaints were reported by the CROS wearers, and many of these related to auditory factors. Both CROS and IROS fittings appear to be effective approaches to the patient with high-frequency hearing loss. However in light of the fewer complaints by the IROS group, and the fact that a large proportion of the CROS complaints related to the amplified signal, IROS appears to be the preferable of the two. The exception involves cases requiring high gain so that CROS might be employed to reduce acoustic feedback.

Consumer Behavior↗
PubMedDate not supplied

Acoustic reflex thresholds: variability and distribution effects.

Acoustic reflex thresholds (ARTs) at 500, 1000, and 2000 Hz from 1833 ears were subjected to multiple linear regression analyses using a stepwise inclusion model to determine the effects of hearing losses in the 500- to 4000-Hz range for each of the activators. Although statistically significant regression equations were developed, these accounted for only 1 to 47% of the variance of ART levels. In light of the wide variance of ARTs unexplainable directly from audiometric data, it was deemed more appropriate to consider the range of ARTs from the standpoint of the sampling distribution of ARTs as a function of hearing level. Deciles were calculated in the 10th through 90th percentile ranges. These data corroborate and expand upon previously reported material on the distributions of ARTs among ears with normal hearing and cochlear impairment.

Adolescent↗
PubMedDate not supplied

Functional hearing loss and its relationship to resolved hearing levels.

The nature of functional hearing loss was retrospectively studied with respect to hearing sensitivity after resolution of the nonorganic components in 63 adults with bilateral exaggerated losses (126 ears). The configuration of the functional components (difference between the functional and resolved thresholds) was found to be related to that of the resolved hearing levels. The size of the functional overlay was essentially the same across the audiometric frequency range when the hearing was actually normal or if there was only mild loss. In cases of precipitously sloping high-frequency losses, the magnitude of the functional overlay became dramatically smaller for the impaired frequencies than for lower frequencies where hearing was normal or only mildly impaired. Moderate and severe losses represented a transitional situation, in which the functional components became gradually smaller with increasing frequency. Subjects with different resolved hearing in each ear (e.g., mild loss in one ear and a precipitous loss in the other) demonstrated nonorganic overlays that were consistent with the actual hearing levels for each respective ear. The findings suggest the use of an internalized, loudness level-based anchor by subjects with functional losses: the test signal must sound as loud as the anchor at each frequency in order for an exaggerated threshold response to be volunteered at that respective frequency. The pure-tone audiometric configuration and amount of functional loss at least in bilateral cases is thus consistently accounted for on the basis of known and explainable auditory factors.

Adult↗
PubMedDate not supplied

Clinical precision of the Rinne test.

The precision of the Rinne test at 128-2048 Hz was studied in 100 ears with confirmed conductive pathologies. The number of negative (diagnostic) Rinnes decreased significantly with fall in frequency. While there were significantly more negative than positive Rinnes at 128 and 256 Hz, there were significantly more positive results at higher frequencies; indicating that the Rinne is not reliably diagnostic above 256 Hz. However, the possibility of vibrotactile responses must be remembered with low frequency tuning forks. Also, conductive lesions manifested as high tone air-bone gaps will not be identified with low frequency Rinne tests. Air-bone gaps of 25 to 40 dB, depending on frequency, are necessary for the Rinne to identify the presence of conductive components in most cases. Gaps of 25-30 dB for 128 Hz; 35-40 dB for 256 Hz; 55-60 dB for 512 Hz; and 45-50 dB for 1024 Hz, are necessary for the Rinne to meet a 75% correct detection criterion. The 2o48 Hz Rinne does not attain even chance detection. The Rinne test cannot be validly employed as a criterion against which other measures can be evaluated.

Acoustic Stimulation↗
PubMedDate not supplied

Temporal summation in acoustic reflex growth functions.

Acoustic reflex growth functions for pure tone activators of 500, 1000 and 2000 Hz and a broad-band noise (BBN) were obtained with activator durations of 20, 200 and 1000 msec (10 msec rise/decay) in four young, normal subjects. The lowest reflex thresholds were obtained for the 1000 msec activators, followed by 200 msec and then 20 msec. The reflex growth functions revealed lower reflex magnitudes for the shorter duration activators. When normalized to account for temporal summation at reflex threshold, reflex magnitude growth was similar among the three durations at 500 Hz, slower for 20 msec than for 200 and 1000 msec at 1000 Hz, and became progressively slower with decreasing duration from 1000 to 200 to 20 msec at 2000 Hz. When expressed in SPL, the BBN growth functions reasonably resembled those at 2000 Hz. No particular pattern was revealed for the normalized BBN growth functions.

Adult↗
PubMedDate not supplied

Binaural and monaural speech discrimination under reverberation.

This study investigated the effects of reverberation upon the speech discrimination performance of 30 normally hearing subjects and 30 persons with bilateral sensorineural hearing loss. Following preliminary tests, the Modified Rhyme Test was administered monaurally and binaurally at reverberation times of 0, 1, 2 and 3 sec. All stimuli were administered under earphones. The lists and conditions were appropriately randomized and counterbalanced so that each subject heard a test list at each reverberation time (RT) monaurally and binaurally. The expected gain due to binaural summation of loudness was simulated in order to test the possibility that any binaural enhancement of intelligibility might be due to binaural loudness summation. For all conditions, the normally hearing subjects performed significantly better than the hearing-impaired group. However, in relative terms, the two groups were remarkably similar. Binaural scores were significantly higher than monaural scores at each RT for both groups (in spite of homophasic conditions). For both groups, monaural and binaural scores decreased with increasing RT. Monaural scores decreased at a significantly faster rate with RT than did the binaural scores (the binaural advantage, however, was larger for the normal group). Increasing the monaural presentation levels to simulate the binaural loudness gain did not result in higher scores. It was concluded that speech discrimination under reverberation is better binaurally than monaurally for both normally hearing and hearing-impaired persons. This is due, at least partly, to the ability of the binaural auditory system to squelch the effects of reverberation. A tentative model is suggested for the binaural squelch of reverberation. The current findings are compared with existing data; and suggestions are offered for clinical application.

Adolescent↗