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July 1974

Cochlear Electrical Activity in Noise-Induced Hearing LossBehavioral and Electrophysiological Studies in Primates

Author Affiliations

Ann Arbor, Mich
From the Kresge Hearing Research Institute and the Department of Otorhinolaryngology, University of Michigan, Ann Arbor.

Arch Otolaryngol. 1974;100(1):36-40. doi:10.1001/archotol.1974.00780040040008

In behavioral and chronic electrophysiological studies on monkeys exposed to octave band noise, cochlear microphonic and action-potential responses to puretone bursts were compared to behaviorally obtained thresholds from the same animals. The following results were obtained: (1) Behavioral pure-tone thresholds were within 3 dB of cochlear action-potential thresholds before noise exposure. However, during recovery from noise exposure, action-potential thresholds were as much as 10 dB lower, suggesting the possibility of physiological "masking." (2) Input-output functions for the cochlear action potentials during these recovery periods strongly resembled loudness recruitment functions, and maximum voltages obtained frequently exceeded preexposure values. Several reasonable explanations for post-exposure loudness recruitment exist, but the basis of the marked transient increase in cochlear electrical activity is still open to speculation. A circulatory rebound phenomenon may be involved.