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Biomedical subjects

R H Margolis

Publications and source records attributed to R H Margolis.

At least 55 records · Page 3Linked to original sources
PubMed1991

Threshold and suprathreshold temporal integration effects in the crossed and uncrossed human acoustic stapedius reflex.

Threshold and suprathreshold temporal integration (TI) effects were studied in the crossed and uncrossed human acoustic stapedius reflex. Changes in reflex threshold were compared at four stimulus durations and for six threshold response criteria; suprathreshold effects were similarly compared at four stimulus durations and at five stimulus sound-pressure levels. Our results showed that reflex thresholds were significantly lower for the uncrossed condition and for longer duration stimuli. Both effects were dependent on threshold response criteria. Threshold TI measurements in both crossed and uncrossed conditions were equivalent at low criterion levels (0%-4%, p greater than 0.05) but were significantly larger in the crossed condition at higher criterion levels (5%-6%, p less than 0.05). Prominent suprathreshold effects also occurred. The main effect was characterized by significantly larger reflex magnitudes in the uncrossed condition. Duration dependent slope differences in magnitude intensity functions (MIFs) were also observed and were characterized by steeper slopes for longer duration stimuli. Saturation effects and/or intensity-dependent slope decelerations in MIFs were predominant in the uncrossed condition and for stimulus durations exceeding 20 ms. These data provide further quantitative evidence for asymmetric threshold and suprathreshold response properties of the crossed and uncrossed human acoustic stapedius reflex and demonstrate the dependence of these effects on stimuli of different durations.

Acoustic Stimulation↗
PubMed1991

Developmental changes in multifrequency tympanograms.

The normal maturational course of tympanometric shape, static aural acoustic admittance and ear canal wall characteristics were investigated in healthy infants, who were followed at various time intervals in the first 4 months of life. Susceptance and conductance tympanograms were recorded from both ears of each subject at four probe frequencies or more. In addition, quantitative pneumatic otoscopy was performed utilizing air pressure changes of the same magnitude as those typically used in tympanometry. Results for the group were an increase in admittance magnitude with increasing age at frequencies above 226 Hz. Admittance phase angle increased with age at all frequencies, indicating a growing contribution of compliant elements in the first 4 months of life. The course of development of input admittance at the tympanic membrane differed among individual infants. Otoscopic findings indicated that external ear canal differences cannot completely account for tympanometric differences between young infants and adults.

Acoustic Impedance Tests↗
PubMed1991

Acoustic reflex measures in audiologic evaluation.

Measurement of the acoustic-stapedius reflex is useful in the diagnosis of certain otologic diseases. The anatomy and physiology of the middle ear muscles and the acoustic reflex arc are reviewed for normal and pathologic ears. The application of acoustic reflex measures to clinical diagnosis is illustrated by a series of case studies.

Auditory Threshold↗
PubMed1991

Audiologic evaluation of the otitis media patient.

Because of the complexity and variability in the expression of otitis media, its effects on auditory function are diverse. The various influences of otitis media on auditory function are described within this article, including acoustic reflex, audiometry, and tympanometry.

Acoustic Impedance Tests↗
PubMed1987

Screening tympanometry: criteria for medical referral.

Tympanograms were obtained from normal preschool and adult subjects with a prototype hand-held tympanometer to obtain normative values for four tympanometric variables: static admittance, equivalent ear canal volume, tympanometric peak pressure, and gradient. Effects of age group, sex, and pump speed (200 or 400 daPa/s) were determined. The results were incorporated into a four-part screening protocol (history, visual inspection, audiometry, and tympanometry) designed to reduce the excessive error rates associated with screening strategies that rely exclusively on tympanometry.

Acoustic Impedance Tests↗
PubMed1986

Simulation of pathological high impedance tympanograms.

The Vanhuyse, Creten, and Van Camp (1975) model for analyzing high frequency tympanograms predicts the shapes of conductance, susceptance, and admittance tympanograms from the relationship between resistance and reactance tympanograms at the tympanic membrane. This model has been applied primarily to low impedance middle-ear pathologies but has not been applied extensively to the more commonly occurring high impedance pathologies. The purpose of this study was to extend the Vanhuyse et al. (1975) model to high impedance pathologies and to identify tympanometric parameters associated with otosclerosis, secretory otitis media, and lateral ossicular fixation. Data from previous experiments on the shape and absolute values of resistance and reactance tympanograms were used to calculate 678-Hz admittance tympanograms that were unique to each of the three high impedance pathologies. Guidelines for differentiating among the middle-ear pathologies on the basis of high frequency tympanometric shapes are presented.

Acoustic Impedance Tests↗
PubMed1986

Tympanometric gradient measured from normal preschool children.

Tympanometric gradient is a quantitative expression of the shape of a tympanogram in the vicinity of the peak. Previous work suggests that gradient measures may be diagnostically and prognostically useful in the assessment and management of middle ear disease. However, since almost all previous work on the subject was performed on tympanograms recorded in 'arbitrary compliance units' which are not comparable to the physical admittance units provided by currently available instrumentation, at this point the tympanometric gradient can only be viewed to be a potentially-useful clinical measure. In this investigation, eight tympanometric gradient measures were calculated from tympanograms obtained from normal preschool age children. The measures were evaluated on the basis of distribution characteristics, relation to static admittance, and effect of pump speed. One of the measures--the pressure interval defined by a 50% reduction in peak eardrum admittance--appears to be the procedure of choice. Measurements obtained from abnormal ears are needed to evaluate the clinical utility of this measurement.

Acoustic Impedance Tests↗
PubMed1985

Magnitude estimation of loudness. III: Performance of selected hearing aid users.

Aided and unaided loudness functions for narrow-band noise stimuli were obtained from hearing-impaired listeners with a magnitude estimation procedure. A comparison of aided loudness functions with those obtained from normal-hearing subjects suggests that the hearing aids did not restore normal loudness relations among the spectral components of speech stimuli. Instead, aided loudness functions tend to reflect an interaction between the abnormal loudness growth that frequently characterizes sensorineural hearing loss and the saturation characteristics of the hearing aid.

Adult↗
PubMed1985

On the loudness of complex stimuli and its relationship to cochlear excitation.

Two experiments were conducted to reexamine the relation between loudness and the bandwidth of complex stimuli. In experiment 1, experimental stimuli consisting of a 2000-Hz pure tone and ten computer-generated multitonal complexes ranging in bandwidth from 0.26-3.16 oct, logarithmically centered at 2000 Hz, were matched in loudness to a 2000-Hz comparison pure tone presented at 90, 70, and 30 dB SPL. The SPL of the experimental stimuli required for equal loudness was linearly related to bandwidth (in octaves) for each of the three comparison stimulus levels. In experiment 2, the loudness behavior of narrow-bandwidth stimuli within the previously reported critical band region was examined. The results indicated a linear relation similar to that obtained in experiment 1. These results are consistent with an auditory filter concept in which frequency is continuously encoded along the basilar membrane and in which loudness of complex stimuli is linearly related to area of excitation.

Acoustic Stimulation↗
PubMed1985

Influence of interaural level differences on the speech recognition masking level difference.

This study was undertaken to determine the effect of interaural level differences on the magnitude of the speech recognition masking level differences obtained from younger and older subjects with normal hearing and from subjects with asymmetrical sensorineural hearing losses. A ten-word subgroup of CID W-1 spondaic words having the largest masking-level differences was used. Masking level differences decreased systematically with increasing interaural level differences for all three groups. At interaural level differences of 36 and 42 dB, the masking level difference persisted for the younger and older normal subjects (1.6 and 1.9 dB, respectively); similar results were obtained from the subjects with hearing losses at a 24-dB interaural level difference. For all subject groups, the S0N0 thresholds were unaffected by changes in the interaural level difference, whereas the S pi N0 thresholds were inversely related to the interaural level difference.

Adult↗
PubMed1985

Multifrequency tympanometry in normal ears.

Susceptance and conductance tympanograms were recorded from 10 normal subjects with probe frequencies ranging from 220 to 910 Hz. Tympanometric shapes progressed through an orderly sequence of patterns, becoming more complex with increasing probe frequency. When the direction of ear-canal air pressure change was from negative to positive values, more complicated tympanometric shapes occurred for all subjects, compared to the positive to negative direction. The results are discussed in relation to the Vanhuyse et al. [Scand. Audiol. 4:45-50, 1975] model of tympanometric shapes. In general, the model is a good first approximation to the distribution of tympanometric patterns from normal ears.

Acoustic Impedance Tests↗
PubMed1984

Magnitude estimation of loudness. I: Application to hearing aid selection.

Three experiments were conducted to explore the utility of magnitude estimation of loudness for hearing aid selection. In Experiment 1 the loudness discomfort level (LDL), most comfortable loudness (MCL), and magnitude estimations (MEs) of loudness were obtained from normal-hearing subjects. MCLs fell within a range of loudness that was relatively low on the loudness function. The LDLs were lower than previously published values. Experiment 2 was performed to identify the source of disparity between our LDL data and previously reported results. The effects of instructions are demonstrated and discussed. In Experiment 3 magnitude estimations of loudness were used to determine the loudness of tonal stimuli selected to represent 1/3 octave band levels of speech. Over the 500-4000 Hz range, the contributions of the various frequency regions to the loudness of speech appears to be nearly constant. Methods are proposed for (a) predicting the frequency-gain response of a hearing aid that restores normal loudness for speech for the hearing-impaired listener and (b) psychophysically evaluating the compression characteristic of a hearing aid.

Audiometry, Pure-Tone↗
PubMed1984

Magnitude estimation of loudness. II: Loudness perception in presbycusic listeners.

Because clinical methods most commonly used for assessing loudness are indirect measures that require one normal or near normal ear, loudness perception has not been studied thoroughly in listeners with symmetrical hearing loss. In this investigation, loudness perception was studied in three groups of listeners: normal listeners, listeners with asymmetrical sensorineural hearing loss, and individuals with bilaterally symmetrical hearing impairment due to presbycusis. In Experiment 1, a Magnitude Estimation of Loudness (ME) technique was compared to Alternate Binaural Loudness Balance ( ABLB ) results for subjects with asymmetrical hearing impairment. Results indicate that ME and ABLB measurements produce similar evidence of abnormally rapid growth of loudness in asymmetrically impaired listeners. In Experiment 2, loudness growth in individuals with normal hearing or with presbycusic hearing impairment was determined from ME measurements. Although presbycusic subjects tended to have steeper loudness functions than normal subjects, the differences did not reach statistical significance except at 6000 Hz, suggesting that, as a group, presbycusic listeners display little, if any, recruitment of loudness.

Adult↗
PubMed1982

A technique for detecting the ipsilateral acoustic reflex.

A technique was explored for detecting the ipsilateral acoustic reflex using one acoustic signal (226-HZ tone) both to elicit the reflex and to measure the impedance of the ear. By eliminating the presentation of two acoustic signals to the same ear, artifactual responses that result from interactions between two signals are avoided. The method provided reflex threshold estimates for five normal subjects that averaged 99.8 dB SPL, in close agreement with previously reported data. A sixth subject, with otosclerosis, showed no evidence of a reflex. With some refinement, the method could become a quick, reliable measurement procedure that avoids some of the problems of conventional methods.

Acoustic Impedance Tests↗