Patterns of Cochlear Adaptation at Three Frequency Regions

Abstract

Auditory adaptation was detd. in four observers to 100-, 1000-, and 4000-c.p.s. tones at 30-, 50-, 70-, and 90-decibel loudness level. The spread of effect to closely adjacent frequencies was particularly examined. The method of adaptation was used to avoid the intrusion of beats in the simultaneous masking expt. Loudness patterns were drawn according to the method of Munson and Gardner, confirming and extending the earlier study. Within the region represented by the differential threshold, no especial peaking of the loudness pattern was found. For example, at 1000 c.p.s., there was a broad peak of [plus or minus] 10 c.p.s. From earlier expts., adaptation is thought to be confined to the peripheral sense organ. According to this view, the present data would represent a stage in the process of handling frequency information, intermediate between the much broader amplitude patterns and the more precise operations at the command of the nervous system.