Journal of the American Auditory Society最新文献

Relationship between acoustic reflex thresholds obtained using conventional and tracking procedures was investigated. In the tracking method, the intensity of the stimulus from a self-recording audiometer is adjusted by the experimenter to bracket the acoustic reflex threshold as visually observed on the meter of an acoustic impedance measuring device. Acoustic reflex thresholds were obtained to pure tones of 500, 1000, and 4000 Hz. High correlations and no significant differences were obtained between the two threshold methods. It was concluded that the tracking method which allows easier control of stimulus parameters and response recording can provide acoustic reflex threshold data similar to those obtained using a conventional method.

The purpose of this study was to describe an acoustic method for measuring temporal characteristics of electroacoustic impedance bridges, and to present data on the temporal responses of three widely used electroacoustic instruments. The potential effects of these instrument parameters on measured characteristics of the acoustic reflex are discussed.

Monosyllabic triplet word intelligibility scores were obtained from normal-hearing and hearing-impaired, loudness-recruiting subjects under two experimental conditions: (1) high-pass (1200 Hz)-filtered, linear amplification, and (2) high-pass (1200 Hz)-filtered, compression amplification using input-to-output ratios of 5:1 and 20:1. Test materials were administered at increased sensation levels of 0, 10, 20, and 30 dB. In general, speech intelligibility was slightly enhanced for normal and hearing-impaired listeners, but only at lower sensation levels. Moreover, the improvement was observed only under the filtered, compression amplification condition for both groups. No important differences were observed between the two compression ratios used. This compression advantage may or may not be observed in clinical hearing aid evaluations.

A brief illustrated atlas demonstrates the progressive relationships of the anatomical structures of the cat's middle ear as one dissects these from the attic approach. There was an attempt to demonstrate the nerves of the lateral semicircular canal and the utricle but without preserving the footplate of the stapes to afford an unobstructed view of the nerves. For the first time, the anatomical features of the cat's middle are are brought together in a progressively illustrated and single source.

Sentence length psychoacoustic material was processed through 16 hearing aids and presented to 220 listeners. Twenty-nine indices of electroacoustic performance were abstracted from a testing program under laboratory conditions. Through a multivariate statistical strategy, psychoacoustic achievement was shown to be positively correlated to and could be predicted by a knowledge of white noise gain, bandwidth below and above 1 kHz, frequency response regularity, and transiet distortion (multiple R = 0.77; F = 2.04; df = 5,10). It was concluded that a multivariate statistical tactic, when used with discretion, can be a useful and powerful tool to predict psychoacoustic performance from a knowledge of hearing aid electroacoustic characteristics.

Fifteen normal infants were seen at the ages of 1, 2, and 3 months. Cardiac responses to auditory stimuli of various frequencies and intensities were evaluated to determine the effects of age of the infant, frequency of the stimulus, and intensity of the stimulus. Heart rate was measured by a fingertip pulse counter and recorded on a polygraph. While the heart rate was being monitored, the infant was presented with a series of tone bursts of 1.5-sec duration with an interstimulus interval of 13.5 sec. Frequencies and intensities of stimuli were found to have no effects on the response. The cardiac rate response was influenced more by the ages of the infants than by stimulus parameters. Variability of the data for two-month-old children seemed to indicate a transition occurring at this age. However, the major influence upon the response was found to be the prestimulus heart rate.

To investigate consonant information in low frequencies, a low-frequency band which contains negligible consonant information in isolation was added to a high-frequency band. There was a significant increase from the high-frequency band-alone score for normal-hearing subjects when the bands were presented at favorable low-frequency/high-frequency bands sensation levels either to the same ear or opposite ears. For congenitally and adventitiously hearing-impaired subjects, there was a significant increase only when the bands were presented to opposite ears. A clinical application of these results is split-band amplification whereby low frequencies were added to one aid and removed from the other aid. Removal of low frequencies from one aid reduces internal noise, attenuates unwanted background noise, reduces cochlear masking, and thus optimally amplifies that part of the speech spectrum which conveys most of the consonant information. The low-frequency response aid adds additional information, including pitch, rhythm, and intonation.

Brainstem-electrical responses were obtained from 10 normal hearing adult subjects using frequency specific tone pips as stimuli. The four frequency specific tone pips (500, 1000, 2000, and 4000 Hz) were diamond shaped with a 2.5-msec rise/fall time. Each tone pip was presented at four intensity levels (70, 50, 30, and 10 dB hearing threshold level), and graphic recordings were made for each frequency at the specific intensity levels. Frequency specific Wave V intensity-latency functions were plotted, and these results were compared to tone pip data obtained in previous studies. In addition, suggested test procedures for obtaining tone pip brainstem-evoked responses under diagnostic conditions are discussed.

Results of a five-year longitudinal study of Meniere's disease in 95 patients is presented. Tests utilized in diagnosis and in determining specific etiology are described. Clinical treatment for patients with Meniere's disease symptoms is discussed. Auditory test results for 101 ears are analyzed. The fluctuating nature of the hearing loss, the poor discrimination for speech, and the limited tolerance for amplification because of the narrow dynamic range present significant problems in utilization of hearing aids for patients with Meniere's disease. A practical approach is suggested for the fitting of hearing aids for these patients.