Suppressor duration effects in forward masking.

Abstract

It has been shown that as the duration of a suppressor increases, the amount of suppression increases in experiments where the suppressor duration was equal to or less than the masker [D. L. Weber and D. M. Green, J. Acoust. Soc. Am. 64, 1392–1399 (1978); R. V. Shannon, ibid. 59, 1460–1470 (1976)]. This suggests that the degree of suppression may be related to the time of interaction between the masker and suppressor. The purpose of this experiment was to evaluate the effects of suppressor duration when the time of masker–suppressor interaction was held constant. Forward-masked thresholds for the 2000-Hz probe were measured with a 2000-Hz masker only (M), and as a function of suppressor duration when the onset of the suppressor preceded the masker (M+S). When the suppressor preceded the masker by 200 ms, the amount of suppression was minimal or absent. The possibility that the threshold change resulted from increased masking by the longer duration suppressor was evaluated by measuring masked threshold for the suppressor alone and by delaying the probe onset relative to the masker–suppressor offset.