Lost silence as a consequence of stream segmentation
Shuji Mori · The Journal of the Acoustical Society of America · 2006
A sequence of successive tones can be segmented into perceptually distinctive streams by inserting a silent gap or by changing the frequency in mid-sequence. This study demonstrates that a silent gap is perceptually lost when the gap coincides with the frequency change that occurs between tones. Even a 40-ms gap is undetectable when the tonal frequency is shifted from 800 to 3200 Hz. One interpretation of this ‘‘lost silence’’ phenomenon is the prioritization of frequency change as a cue for auditory segmentation. A silent gap and a change in frequency both mark a stream boundary if they are salient. They will be redundant as boundary markers when they coincide with each other; the frequency change will preempt the priority in auditory processing, whereas gap information will receive little processing and eventually become indiscernible. This phenomenon might be related to perceptual ambiguity of the temporal relation of separate streams (Van Noorden, 1975). [Work supported by JSPS.]