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Biomedical subjects

S J Barry

Publications and source records attributed to S J Barry.

25 records · Page 2Linked to original sources
PubMed1978

Absolute thresholds for frequency-modulated signals: effects of rate, pattern, and percentage of modulation.

Absolute monaural thresholds for continuous unmodulated and frequency-modulated signals were determined for five normal-hearing subjects using the method of adjustment. Three carrier signals (250, 1000, and 4000 HZ) were modulated at rates of 2 and 20 times per sec using frequency deviations of +/- 5, 10, and 20%, and both ramp and sinusoidal modulation. Thresholds measured at the slower modulation rate were 5 to 10 dB lower than those measured for unmodulated signals at the two higher test frequencies. Suggestions are presented as to how the clinician may minimize the possible discrepancy between modulated and unmodulated signals using currently available warble-tone equipment.

Adult↗
PubMed1978

Physical and physiological constraints on the use of bone-conduction speech audiometry.

Several authors have recommended the use of bone-conduction speech audiometry, and the literature supports the clinical value of this procedure. It has been claimed that bone-conduction output for speech can be increased to 110-dB HL with the Radioear B-70-A vibrator through supplementary amplification, but this claim is unsubstantiated by objective measurements. Available technical data indicate that the maximum output level attainable with this virbator without incurring serious distortion is 65- to 70-dB HL at midfrequencies and substantially less at lower frequencies. Both behavioral and electromechanical data are presented which show, not only that 70-dB HL is the absolute maximum hearing level for speech attainable through the B-70-A vibrator without serious deterioration of speech-discrimination scores in normal listeners, but also that this appears to be very close to the maximum vibratory level that human observers can comfortably tolerate.

Audiometry↗
PubMed1978

The effect of sectioning auditory centrifugal fibers on the cochlear microphonic and action potential in guinea pigs.

This investigation on 8 guniea pigs determined the immediate effect on the cochlear microphonic (CM) and action potential (AP) of ipsilateral sectoning of the autitory centrifugal fibers. An acoustic signal was used to evoke the CM and AP of one ear of guinea pig and the homolateral olivo-cochlear bundle and lateral lemniscus were then sectioned. Differences between pre- and post-section CM and AP were measured. The results demonstrated an increase in the CM and a decrease in the AP in all animals. Speculation with regard to the overall function of the auditory centrifugal system was offered.

Action Potentials↗
PubMedDate not supplied

Comparison of acoustic reflex and behavioral thresholds as a function of stimulus frequency and duration.

Threshold-duration functions for the acoustic reflex and threshold-duration functions based upon behavioral measures were obtained on the same group of subjects and compared. The mean temporal integration for the acoustic reflex threshold appears to be comparable to that for the behavioral threshold for stimuli of 500, 1000, and 2000 Hz, but marked individual differences exist in temporal integration of the acoustic reflex. At 4000 Hz, the mean change in the reflex threshold as a function of stimulus duration is significantly greater than the change in the behavioral threshold under the same conditions, suggesting that in the elicitation of the acoustic reflex the auditory system processes energy less efficiently at 4000 Hz than it does at lower frequencies.

Acoustic Stimulation↗