Properties of auditory stream formation

Abstract

A sequence of sounds may be heard as coming from a single source (called fusion or coherence) or from two or more sources (called fission or stream segregation). Each perceived source is called a ‘stream’. When the differences between successive sounds are very large, fission nearly always occurs, whereas when the differences are very small, fusion nearly always occurs. When the differences are intermediate in size, the percept often ‘flips’ between one stream and multiple streams, a property called ‘bistability’. The flips do not generally occur regularly in time. The tendency to hear two streams builds up over time, but can be partially or completely reset by a sudden change in the properties of the sequence or by switches in attention. Stream formation depends partly on the extent to which successive sounds excite different ‘channels’ in the peripheral auditory system. However, other factors can play a strong role; multiple streams may be heard when successive sounds are presented to the same ear and have essentially identical excitation patterns in the cochlea. Differences between successive sounds in temporal envelope, fundamental frequency, phase spectrum and lateralization can all induce a percept of multiple streams. Regularities in the temporal pattern of elements within a stream can help in stabilizing that stream.

The initial phase of auditory and visual scene analysis

“…However, both first percept bias and inertia are observed for auditory streaming, where the first percept is also biased towards one stream (grouped) and it lasts longer than subsequent one-stream percepts. Together, these effects correspond to the classic and much studied build up of auditory streaming [7]. Here we showed that, for visual plaids, first percept bias and inertia corresponded to two independent phenomena: parametric manipulations could influence first percept inertia without affecting first percept bias.…”

Multistability in auditory stream segregation: a predictive coding view

“…The underlying idea is that the more similar (proximal in feature space) two individual sound events are, the more likely it is that they were emitted by the same sound source, and, therefore, binding them together is more likely to result in veridical perception. Many different acoustic features can influence the sense of similarity; these are described in detail by Moore & Gockel [39] (see also Moore & Gockel [40]). …”

Physiology, Psychoacoustics and Cognition in Normal and Impaired Hearing

“…Consistent with Gestalt grouping principles (Köhler 1947), auditory streaming experiments show that featural separation (such as pitch differences) promote segregation and conversely that featural similarity promotes integration Moore and Gockel 2012). It is also known that within-stream (within-pattern) comparisons are far easier to make than between stream comparisons; (e.g.…”