Acoustic Reflex Threshold-Duration Functions for Normals and Noise-Induced Permanent Threshold Shift.

The purpose of this investigation was to compare the effects of temporal auditory integration on the acoustic reflex thresholds for subjects with normal hearing and for subjects with noise-induced permanent threshold shift. Threshold-duration functions were determined for 1, 2, and 4 KHz pure tones and for broad-band noise.

Acoustic reflexes were monitored using an impedance technique. Stimulus durations employed were 20, 50, 100, 200, and 500 msec. A measurement technique was developed which included observation of the impedance bridge output deflections in conjunction with latency time to confirm the occurrence of reflex activity.

Results of the study indicated that there may be flattening of acoustic reflex threshold-duration functions for persons having noise-induced hearing losses. Flattened functions appeared to be frequency specific and corresponded to areas of hearing loss. The degree of flattening of the functions was related to the degree of the hearing loss, with flatter functions occurring for greater hearing losses.

Major is listed as Audiology.