How many streams?

[Michael Norris <michaeln@xxxxxxxxxxxxxx>]

Dear List,

        The gradual build and decay of auditory streaming has been
        measured, and the persistence of stream biasing is reported
        to be about 4 seconds [1][2][3], but once streams have formed,
        what happens when a tone sequence in a different frequency
        range is added to the pattern?

        If you take four tones, A,B,C,D in two clusters, separated by
        say, 3, 7 and 3 semitones (similar to stimuli used in [1])


          0s      4s      8s      12s
A/B     - _ - _ - _ - _ - _ - _ - _ - _ - _ - _

C/D                    - _ - _ - _ - _ - _ - _ -

(numbers of tones not to scale in this diagram;
        labels 1, 2, &c are 4sec apart)


        0s:  A and B form one stream

        4s:  A and B split into two streams

        8s:  Now what? - Are there one, two, or three streams?
                Does the whole system reset and form a single
                stream, or do C and D form one stream while
                A and B rejoin to form another, or do A and B
                remain segregated while C and D begin fused.

        12:  Now do we have two streams or four?
                Can the presence of C and D prevent A and B from
                segregating?


        any leads/references appreciated,

thanks,

Michael Norris
michaeln@csee.uq.edu.au

----------------------- /\/\/\/- -------------------------------------

[1] A.S. Bregman (1978) "Auditory streaming is cumulative"
        Journal of Experimental Psychology: Human Perception
        and Performance 4:3,380-387
[2] M.W. Beauvois and R. Meddis (1997) "Time decay of auditory
        stream biasing" Perception and Psychophysics 59:1,81-86
[3] W.L. Rogers and A.S. Bregman (1998) "Cumulation of the
        tendency to segregate auditory streams: Resetting
        by changes in location and loudness" Perception and
        Psychophysics 60:7,1216-1227