Cochlear Masking and Adaptation

Abstract

Intracochlear electrodes were used to measure the action potentials (AP) generated by successive clicks. During a series of clicks the AP decreases in a specific way. This decrease is called by many investigators adaptation of central origin. It is influenced by repetition rate, intensity and masking by noise or tone. It was found that adaptation and readaptation are controlled by the positive after-potential generated by a click or a tone or noise burst. Also a positive phenomenon like the +SP could influence the magnitude of the AP. It is postulated that this fast adaptation is influenced by a positive DC potential in the vicinity of the hair-cells, and thus must be of cochlear origin. A long-term adaptation due to our low intensity stimulus could not be demonstrated. It is possible that peripheral (fast) and central (slow) adaptation act in the same way on different intensity levels, by causing a +DC potential around the hair-cells.

These investigations were supported in part by a grant from the Netherlands Organisation for the Advancement of Pure Research. (Z.W.O.)