NOTE: This website is an archived copy of Al Bregman's personal website, created with the permission of Abigail Sibley and Christopher Lyons. Copyright (c) 2008 Al Bregman.

History

My own involvement with the topic of ASA dates back to 1969, when I observed a phenomenon that I called "auditory stream segregation": at high speeds, a rapid sequence of alternating high and low tones would split perceptually into separate high and low streams. (See and listen to this demo from the CD). The effect was to perceptually isolate the patterns of pitches in the two streams. Patterns that were contained entirely within a stream were easy to recognize but those that involved tones in different streams were recognized at a chance level.

My subsequent research has uncovered a number of principles of grouping, some similar to those in vision, others unique to auditory perception, that deal with the ASA problem. Some of them resemble the principles of grouping discovered by the Gestalt psychologists in the early twentieth century.

A number of auditory phenomena have been related to the grouping of sounds into auditory streams. They include speech perception, the perception of the order and other temporal properties of sound sequences, the combining of evidence from the two ears, the perception of numerosity, the perception of patterns by infants, the detection of patterns embedded in other sounds, the perception of simultaneous "layers" of sounds (e.g., in music), the perceived continuity of sounds through interrupting noise, perceived timbre and rhythm, and the perception of tonal sequences (reviewed in Bregman, 1990/1994)