Perstimulatory loudness adaptation in selected cochlear impaired and masked normal listeners.

Abstract

Two experiments were performed to determine the magnitude of threshold and suprathreshold adaptation for subjects with cochlear impairment due to noise exposure and normal listeners whose thresholds were raised by an external masking noise. For both groups, minimal loudness adaptation was observed near threshold (10 or 20 dB SL), but at higher intensity levels (20 to 30 dB SL), no loudness adaptation was measured over a 3-min period. The results of the threshold adaptation tests also indicated some adaptation near threshold. On an alternate binaural-loudness balance task, virtually complete loudness recruitment was found above 20-dB sensation level. The results suggest (1) that loudness adaptation and loudness growth in the cochlear impaired and masked ear at sensation levels beyond 20 dB reflect behavior for loudness similar to that found among normal-hearing subjects at comparable intensity levels and (2) cochlear impaired, masked normal, and unmasked normal listeners demonstrate comparable loudness adaptation behavior at low sensation levels.