Separating the Effects of the Acoustic Reflex from Remote Masking

Two experiments were performed in order to separate the effects of the acoustic reflex from remote masking. In the first experiment, subjects adjusted the level of a 400-Hz maskee in the homolateral ear in order to keep the perceived sound source centered when presented binaurally simultaneously with the 3000-Hz monaural masker for various durations, some of which were shorter than the latency of the acoustic reflex. The results of the first experiment show remote masking at durations of 50, 200, and 500 msec, with significantly more masking at 500 msec than at 50 msec. In the second experiment, some procedural refinements were made and durations as short as 20 msec were used. Results again showed remote masking taking place at durations much shorter than the latency of the acoustic reflex and significantly more remote masking at 500 msec than at 20 msec. The results of both experiments seem to support notions of the involvement of distortion products in remote masking at short durations and the additional involvement of the acoustic reflex at longer durations.