The Build-up of Auditory Stream Segregation: A Different Perspective

Abstract

The build-up of auditory stream segregation refers to the notion that sequences of alternating A and B sounds initially tend to be heard as a single stream, but with time appear to split into separate streams. The central assumption in the analysis of this phenomenon is that streaming sequences are perceived as one stream at the beginning by default. In the present study, we test the validity of this assumption and document its impact on the apparent build-up phenomenon. Human listeners were presented with ABAB sequences, where A and B were harmonic tone complexes of seven different fundamental frequency separations (Δf) ranging from 2 to 14 semitones. Subjects had to indicate, as promptly as possible, their initial percept of the sequences, as either “one stream” or “two streams,” and any changes thereof during the sequences. We found that subjects did not generally indicate a one-stream percept at the beginning of streaming sequences. Instead, the first perceptual decision depended on Δf, with the probability of a one-stream percept decreasing, and that of a two-stream percept increasing, with increasing Δf. Furthermore, subjects required some time to make and report a decision on their perceptual organization. Taking this time into account, the resulting time courses of two-stream probabilities differ markedly from those suggested by the conventional analysis. A build-up-like increase in two-stream probability was found only for the Δf of six semitones. At the other Δf conditions no or only minor increases in two-stream probability occurred. These results shed new light on the build-up of stream segregation and its possible neural correlates.

Functional brain networks underlying idiosyncratic switching patterns in multi-stable auditory perception

“…Traditionally, it has been assumed that integration is the default mode of auditory processing in stream segregation and that it requires time to build-up separate streams (Anstis and Saida, 1985;Bregman, 1990), although this assumption has been challenged (Deike et al, 2012;Denham et al, 2013). The current data is incompatible with the assertion that a default mode of the auditory system processes sound sequences in terms of the integrated organization, because in close to one-fifth of the experimental blocks, integration was not the first reported percept.…”

“…The initial perception of this stimulus is strongly influenced by the stimulus parameters, with larger separation between "A" and "B" and faster presentation rates promoting the perception of the segregated and the opposite the integrated percept (for a review see Moore and Gockel, 2012). However, for longer (>30 s) stimuli, perception inevitably switches between the alternative percepts (Anstis and Saida, 1985;Bendixen et al, 2010;Deike et al, 2012;Denham and Winkler, 2006;Gutschalk et al, 2005;Pressnitzer and Hupé, 2006) and the effects of the stimulus parameters are reduced at longer delays from the stimulus onset (Denham et al, 2013).…”

Feature Predictability Flexibly Supports Auditory Stream Segregation or Integration

“…This suggests that all organizations are "equal" in that they must be supported by cues present in the auditory input. This conclusion is consistent with other recent work challenging the view of "integration by default" [9,46].…”

The effect of stimulus context on the buildup to stream segregation

“…One issue with attention is whether the behavioral response is measuring the buildup, or the time to perceptual decision (Deike et al, 2012). Additionally, performing a task or attending to a subset of sounds may influence threshold levels for detecting segregation (Sussman et al, 1998a, 2005; Sussman, 2007; Sussman and Steinschneider, 2009).…”