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Biomedical subjects

H J Greenberg

Publications and source records attributed to H J Greenberg.

11 recordsLinked to original sources
PubMed1979

Effects of ethyl alcohol on the contralateral and ipsilateral acoustic reflex threshold.

Contralateral and ipsilateral acoustic reflex thresholds were measured in response to 500-, 1000-, and 2000-Hz pure tones after the ingestion of a 50% alcohol solution. Acoustic reflex threshold measurements were obtained preingestion and at blood-alcohol concentrations of 0.03 to 0.10% in 0.01% increments. A linear relationship existed between acoustic reflex threshold and blood-alcohol concentration, with the greatest shift at 0.10% being 11 dB for contralateral stimulation and 7 dB for ipsilateral. No frequency effects were found. Results can be explained by the anatomical differences in the contralateral and ipsilateral pathways.

Adult↗
PubMed1979

Relationship between loudness discomfort level and acoustic reflex threshold for normal and sensorineural hearing-impaired individuals.

The relationship between loudness discomfort level (LDL) and acoustic reflex threshold (ART) was determined by comparing the ART to the LDL obtained by the psychophysical method of constant stimuli. Randomly presented stimuli of 1000 Hz, 2000 Hz, and a multi-talker speech noise were presented to normal and sensorineural hearing-impaired listeners. The listener's task was to judge whether the stimulus was at a level that was: (1) too loud or uncomfortably loud; or (2) not too loud or not uncomfortably loud. Prior to the judgement of the subject acoustic reflex threshold were determined. Both LDL and ART were found to be significantly higher for the hearing-impaired group. For the pure tone stimuli, LDL for the hearing-impaired group was at or below the ART. Significant differences were shown to exist between LDL and ART for each group. A multiple regression analysis indicated significant correlations between LDL and ART. Ranges of prediction error were selected to investigate the ability of ART to predict LDL. Both pure tone and speech ART successfully predicted LDL within +/- 10 dB for a high percentage of the subjects.

Adolescent↗
PubMed1979

Speech intelligibility in stapedectomized individuals.

We assessed the types of speech errors made in relation to the acoustic reflex. Ten subjects with unilateral stapedectomies were presented with consonant-vowel nonsense syllables in low pass noise at 70, 95, and 110 dB SPL in each ear. Hearing sensitivity for all subjects was normal or near-normal bilaterally. In the operated ear, speech intelligibility was significantly poorer than in the unoperated ear at all intensity levels. A distinctive feature analysis supported this finding. The data suggest that word discrimination testing in quiet does not adequately reveal the success of stapedectomy surgery. The distinctive feature analysis indicated that rather than consider the acoustic reflex as limiting the forward spread of masking into high frequencies, it would be better to describe it as a general aural overload regulator.

Acoustic Stimulation↗
PubMed1977

Clinical acoustic reflex threshold measurements in infants.

Acoustic reflex thresholds elicited using clinical acoustic impedance techniques were obtained on normal infants between one month and one year of age. Reflex activating signals of 500, 1000, 2000 Hz, low-pass, high-pass, and white noise were used. Less intensity was required to elicit the acoustic reflex to the noise than to the pure tones, with the 500-Hz tone requiring the greatest intensity. Inference of auditory thresholds from the acoustic reflex indicated the presence of normal hearing in the infant group.

Acoustic Impedance Tests↗
PubMedDate not supplied

Influence of ear canal air pressure on acoustic reflex threshold.

This study was undertaken to investigate the effects of ear canal air pressure variation on the threshold of acoustic reflex. The acoustic reflex threshold was obtained to 500 and 1000 Hz activating signals as pressure was varied between +/- 200 mm H2O. The results demonstrated a reduction in sensitivity of the acoustic reflex with variations in positive or negative air pressure. Observation of the conductance component of admittance consistently required higher intensity levels to elicit the acoustic reflex. Clinical implications are that external air pressure can vary within a range of +/- 80 mm H2O and continue to maintain the acoustic reflex threshold close to its value obtained at maximum compliance.

Adult↗
PubMedDate not supplied

Acoustic reflex thresholds using conventional and tracking methods.

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.

Audiometry↗
PubMedDate not supplied

Effects of ethyl alcohol on the acoustic reflex threshold.

Acoustic reflex thresholds for pure tones and white nose were measured every 20 min for 4 hr after the ingestion of ethyl alcohol. The average maximum acoustic reflex threshold shift was 11 dB, occurring on the average at 100 min, and returning to base-line levesl at approximately 200 min postingestion. These data lend support to the classification of ethyl alcohol as a sedative, and should caution the clinician when interpreting acoustic reflex threshold data from persons who have ingested small amounts of alcohol.

Adult↗
PubMedDate not supplied

Acoustic admittance of the ear in the geriatric person.

The effects of age on acoustic admittance in a geriatric population were investigated in persons ranging in age from 50 to beyond 70 years. The results demonstrated a significant decrease in admittance for the 70-year-old group, with the change being primarily attributable to a decrease in susceptance. Women consistently demonstrated lower admittance than men. The data obtained suggest that different norms for static admittance be applied to persons above 70 years of age.

Acoustics↗
PubMedDate not supplied

Effects of human middle ear muscle contractions on speech intelligibility.

The present study assessed the relationship between the acoustic reflex and speech intelligibility. Monosyllabic words mixed with noise were presented at -6, -3.0 and +3 dB signal-to-noise ratios. The word lists were presented with a 2000-Hz tone in the contralateral ear at a level 15 dB above or 20 dB below the acoustic reflex threshold to evaluate intelligibility differences with the acoustic reflex contracted and relaxed. The results indicated that a significant decrement in speech intelligibility differences with the acoustic reflex contracted and relaxed. The results indicated that a significant decrement in speech intelligibility occurred with the reflex contracted at signal-to-noise ratios of -3, and 0 dB. Slight but not significant decrements were seen at -6 and +3 dB signal-to-noise ratios. These results are discussed along with possible reasons for the lack of agreement with previous research.

Adult↗
PubMedDate not supplied

Temporal summation of the acoustic reflex in normal and sensorineural hearing-impaired ears.

Psychophysical and acoustic reflex temporal summation measures were obtained on normal-hearing and sensorineural hearing-impaired persons. Bursts of one-third octave noise with center frequencies of 500, 1000, 2000, and 4000 Hz and durations of 15, 20, 50, 100, 200, and 300 msec were used as stimuli. Reflexes were obtained using an acoustic impedance measuring technique. Results demonstrated that the duration of the noise stimuli had a profound effect on the acoustic reflex response and that the ear with Ménière's disease was clearly distinguishable from the normal ear by both psychophysical and acoustic reflex temporal summation measurements. The presbycusic subjects were separated from the normal subjects to a greater extent in the psychophysical data at the higher frequencies. The reflex thresholds for the noise bands and durations used in this study occurred at lower sound pressure levels than those previously obtained. The normal-hearing subjects failed to show any differences in either psychophysical or acoustic reflex temporal summation as a function of stimulus frequency.

Acoustic Stimulation↗