Multistability in auditory stream segregation: a predictive coding view

Abstract

Auditory stream segregation involves linking temporally separate acoustic events into one or more coherent sequences. For any non-trivial sequence of sounds, many alternative descriptions can be formed, only one or very few of which emerge in awareness at any time. Evidence from studies showing bi-/multistability in auditory streaming suggest that some, perhaps many of the alternative descriptions are represented in the brain in parallel and that they continuously vie for conscious perception. Here, based on a predictive coding view, we consider the nature of these sound representations and how they compete with each other. Predictive processing helps to maintain perceptual stability by signalling the continuation of previously established patterns as well as the emergence of new sound sources. It also provides a measure of how well each of the competing representations describes the current acoustic scene. This account of auditory stream segregation has been tested on perceptual data obtained in the auditory streaming paradigm.

Feature Predictability Flexibly Supports Auditory Stream Segregation or Integration

“…The precise mechanism by which predictability acts upon auditory scene analysis is still unclear. One interpretation that is consistent with the available evidence suggests that detecting the presence of a predictable pattern stabilizes the corresponding auditory stream by increasing the perceptual coherence of its elements, thus making this stream easier to maintain for longer periods of time [5,17,18,30]. If this interpretation is correct, then the same mechanism should apply when the listener perceives only one stream -in other words, predictable patterns should stabilize an integrated percept when compared to an arrangement of similar tones with randomly jittered feature values.…”

“…The independent manipulation of predictability was possible by systematically changing the sequential linkage between successive tones within each set ('A-A-A' and 'B-B-B') or across the sets ('A-B' and 'B-A'). Tones that are predictive of each other can be assumed to be more strongly linked in perception, and thus should be more likely to form a coherent stream [16][17][18]33]. This Manuscript submitted to Acta Acustica Bendixen et al 18 idea had been empirically demonstrated by introducing predictability separately into the 'A' and 'B' tone sets and showing that this increases stream segregation relative to an unpredictable control condition [5,30].…”

“…With prolonged exposure to such sequences, perception switches back and forth between the integrated and segregated (and possibly Manuscript submitted to Acta Acustica Bendixen et al 5 other) alternatives [8][9][10][11][12][13][14][15]. This perceptual bi-or multistability has been interpreted as a sign of the system exploring different grouping alternatives [16][17][18].…”

“…This was achieved by systematically changing the sequential dependencies between successive tones within and/or across the 'ABA-' triplets, such that these tones would or would not be predictive of each other. In the framework suggested by [18], this corresponds to strengthening or weakening the links between pairs of sounds, which would have immediate consequences on their perceptual coherence (see also [33]). …”

Audio-visual synchrony and feature-selective attention co-amplify early visual processing

“…We suggest that this paradox can be solved by assuming that our concurrent flicker and pulse stimulation at distinct (and incommensurable) rates led to a perceptual dissociation of the visual stimulus into two distinct streams over time -a phenomenon well described as stream segregation in auditory perception (reviewed in Winkler et al 2012). …”