Illusory continuity of intermittent pure tone in binaural listening and its dependency on interaural time difference

Illusory continuity is known as a psychoacoustical phenomenon in hearing; i.e. an intermittent pure tone may be perceived as if it was continuous, when it is padded with enough large white noise. There are many researches related to this issue in monaural listening. It is said that such illusory continuity is observed when there is no evidence of discontinuity and level of the white noise is large enough to mask the pure tone. In this paper, we investigated illusory continuity in binaural listening, and measured its threshold levels according to some interaural time differences (ITDs). The ITDs simulate a sense of direction about sound sources and give new information for evidence of discontinuity, which should be expected to promote the illusory continuity. As a result, the threshold level of illusory continuity in binaural listening depended on ITDs between tone target and noise masker. The increase of threshold level was minimum when the target and masker had the same ITD.