Reductions in overshoot following intense sound exposures.
Overshoot refers to the poorer detectability of brief signals presented soon after the onset of a masking noise compared to those presented after longer delays. In the present experiment, brief tonal signals were presented 2 or 190 ms following the onset of a broadband masker that was 200 ms in duration. These two conditions of signal delay were tested before and after a series of exposures to a tone intense enough to induce temporary threshold shift (TTS). The magnitude of the overshoot was reduced after the exposure when a TTS of at least 10 dB was induced, but not when smaller amounts of TTS were induced. The reduction in overshoot was due to a decrease in the masked thresholds with the 2-ms delay; masked thresholds with the 190-ms delay were not different pre- and post-exposure. The implication is that the mechanisms responsible for the normal overshoot effect are temporarily inactivated by the same stimulus manipulations that produce a mild exposure-induced hearing loss. Thus the result is the paradox that exposure to intense sounds can produce a loss of signal detectability in certain stimulus conditions and a simultaneous improvement in detectability in other stimulus conditions.
Champlin
C A
CA
Department of Psychology, University of Texas, Austin 78712.
McFadden
D
D
D000161:Acoustic Stimulation; D000222:Adaptation, Physiological; D000293:Adolescent; D000328:Adult; D001305:Auditory Fatigue / Q000502:physiology*; D001309:Auditory Threshold / Q000502:physiology*; D006801:Humans; D008297:Male; D010470:Perceptual Masking / Q000502:physiology; D011930:Reaction Time / Q000502:physiology