The effect of tone duration on auditory stream formation

cote interne IRCAM: Beauvois98a/National audienceIn a study in which the effect of tone duration on the formation of auditory streams was investigated, subjects were presented with 15-sec alternating pure-tone sequences(ABAB...) and were asked to orient their attention over theduration of the sequence toward hearing either a temporallycoherent or a segregated percept. At stimulus offset, thesubjects indicated whether their percept at the end of thestimulus had been that of a temporally coherent ABAB trillor that of segregated A and B streams. The experimentalresults indicated that the occurrence of stream segregationincreases as (1) the duration of the A and B tones increasesin unison and (2) the difference in duration between the A and B tones increases, with the duration difference betweenthe tones producing the strongest segregation effects. Acomparison of these experimental results with those of otherstudies strongly suggests that the time interval betweenthe offset and onset of consecutive tones in the same frequencyrange is the most important temporal factor affecting auditorystream formation. Furthermore, a simulation of the experimentalresults by the Beauvois and Meddis (1996) stream segregationmodel suggests that both the tone duration effects reportedhere and Gestalt auditory grouping on the basis of temporalproximity can be understood in terms of low-levelneurophysiological processes and peripheral-channeling factors