The "overshoot" effect and sensory hearing impairment.

The threshold for the detection of a brief tone masked by a longer-duration noise burst is higher when the tone is presented shortly after the onset of the noise than at longer delay times. This finding has been termed the "overshoot" effect [E. Zwicker, J. Acoust. Soc. Am. 37, 653-663 (1965)]. The present letter compared the size of the effect in the better and more impaired ear of six subjects with high-frequency unilateral or asymmetric hearing losses of sensory origin. Thresholds were measured for 5-ms 4-kHz tones presented 10, 200, and 390 ms after the onset of a 400-ms, 2- to 8-kHz noise burst. The better ear of each subject was tested using two noise levels, one equal in sound-pressure level and one equal in sensation level to that used for the impaired ear. Thresholds for all subjects and all ears decreased monotonically with increasing delay time, with the size of the effect typically 5 dB. Thus a small overshoot effect was observed regardless of hearing impairment.