ASA 125th Meeting Ottawa 1993 May

3pMU7. The contribution of onset, offset, and comodulation to the grouping of noise bands.

Christian Kaernbach

Inst. fur Neuroinformatik, Univ. Bochum, Postfach 10 21 48, 4630 Bochum, Germany

Auditory grouping uses two difference kinds of cues; ``vertical'' curs act on small temporal sections and are based on similarity principles (frequency, harmonicity, onset/offset, modulation), whereas ``horizontal'' (sequential) cues depend on the history of the stimulus. The present study addresses the relative importance of several vertical grouping cues. Twenty naive subjects were presented with auditory scenes of one to five elements. The elements were noise bands with a width of 50 Hz and a duration of 0.12 to 0.36 s. The center frequencies, the onsets and the offsets were randomized; in half of the scenes the noise bands were comodulated. The subjects were asked how many events they had heard. The number of perceived auditory events was on the average smaller than the number of presented noise bands. This could be shown to depend mostly on onset synchrony, to a slightly smaller degree on offset synchrony, and only very little on comodulation.