Perceptual organization of complex auditory sequences: Effect of number of simultaneous subsequences and frequency separation (original) (raw)

Brochard et al. - Journal of experimental psychology. Human perception and performance - 1999

Previous findings on streaming are generalized to sequences composed of more than 2 subsequences. A new paradigm identified whether listeners perceive complex sequences as a single unit (integrative listening) or segregate them into 2 (or more) perceptual units (stream segregation). Listeners heard 2 complex sequences, each composed of 1, 2, 3, or 4 subsequences. Their task was to detect a temporal irregularity within 1 subsequence. In Experiment 1, the smallest frequency separation under which listeners were able to focus on 1 subsequence was unaffected by the number of co-occurring subsequences; nonfocused sounds were not perceptually organized into streams. In Experiment 2, detection improved progressively, not abruptly, as the frequency separation between subsequences increased from 0.25 to 6 auditory filters. The authors propose a model of perceptual organization of complex auditory sequences.

Stability of Perceptual Organisation in Auditory Streaming

The Neurophysiological Bases of Auditory Perception, 2010

In everyday situations, we perceive sounds organized according to their source, and can follow someone's speech or a musical piece in the presence of other sounds without apparent effort. Thus it is surprising that recent evidence obtained in the most widely used experimental test-bed of auditory scene analysis, the two-tone streaming paradigm, demonstrated extensive bistability even in regions of the parameter space previously thought to be strongly biased towards a particular organisation. This raises the question of what aspects of the rich natural input allow the auditory system to form stable representations of concurrently active sound sources. Here we report the results of perceptual studies aimed at testing this issue. It is possible that the extreme repetitiveness of the alternating two-tone sequence, i.e., lack of change, causes perceptual instability. Our first experiment addressed this hypothesis by introducing random changes in the stimulation. It is also possible that under natural conditions, multiple redundant cues stabilize perception. The second experiment tested this hypothesis by adding a second cue which favoured one organisation.

When acoustic sequences are not perceptual sequences: The global perception of auditory patterns

Perception & Psychophysics, 1993

found that when sequences consisting of 10 40-msec steady-state vowels were presented in recycled format, minimal changes in order (interchanging the position of two adjacent phonemes) produced easily recognizable differences in verbal organization, even though the vowel durations were well below the threshold for identification of order. The present study was designed to determine if this ability to discriminate between different arrangements of components is limited to speech sounds subject to verbal organization, or if it reflects a more general auditory ability. In the first experiment, 10 40-msec sinusoidal tones were substituted for the vowels; it was found that the easy discrimination of minimal changes in order is not limited to speech sounds. A second experiment substituted 10 40-msec frozen noise segments for the vowels. The succession of noise segments formed a 400-msec frozen noise pattern that cannot be considered as a sequence of individual sounds, as can the succession of vowels or tones. Nevertheless, listeners again could discriminate between patterns differing only in the order of two adjacent 40-msec segments. These results, together with other evidence, indicate that it is not necessary for acoustic sequences of brief items (such as phonemes and tones) to be processed as perceptual sequences (that is, as a succession of discrete identifiable sounds) for different arrangements to be discriminated. Instead, component acoustic elements form distinctive "temporal compounds," which permit listeners to distinguish between different arrangements of portions of an acoustic pattern without the need for segmentation into an ordered series of component items. Implications for models dealing with the recognition of speech and music are discussed.

Regular patterns stabilize auditory streams

The Journal of the Acoustical Society of America, 2010

The auditory system continuously parses the acoustic environment into auditory objects, usually representing separate sound sources. Sound sources typically show characteristic emission patterns. These regular temporal sound patterns are possible cues for distinguishing sound sources. The present study was designed to test whether regular patterns are used as cues for source distinction and to specify the role that detecting these regularities may play in the process of auditory stream segregation. Participants were presented with tone sequences, and they were asked to continuously indicate whether they perceived the tones in terms of a single coherent sequence of sounds (integrated) or as two concurrent sound streams (segregated). Unknown to the participant, in some stimulus conditions, regular patterns were present in one or both putative streams. In all stimulus conditions, participants' perception switched back and forth between the two sound organizations. Importantly, regular patterns occurring in either one or both streams prolonged the mean duration of two-stream percepts, whereas the duration of one-stream percepts was unaffected. These results suggest that temporal regularities are utilized in auditory scene analysis. It appears that the role of this cue lies in stabilizing streams once they have been formed on the basis of simpler acoustic cues.

Temporal predictability as a grouping cue in the perception of auditory streams

The Journal of the Acoustical Society of America, 2013

This study reports a role of temporal regularity on the perception of auditory streams. Listeners were presented with two-tone sequences in an A-B-A-B rhythm that was either regular or had a controlled amount of temporal jitter added independently to each of the B tones. Subjects were asked to report whether they perceived one or two streams. The percentage of trials in which two streams were reported substantially and significantly increased with increasing amounts of temporal jitter. This suggests that temporal predictability may serve as a binding cue during auditory scene analysis.

Effects of context on auditory stream segregation

Journal of Experimental Psychology: Human Perception and Performance, 2008

The authors examined the effect of preceding context on auditory stream segregation. Low tones (A), high tones (B), and silences (Ϫ) were presented in an ABAϪ pattern. Participants indicated whether they perceived 1 or 2 streams of tones. The A tone frequency was fixed, and the B tone was the same as the A tone or had 1 of 3 higher frequencies. Perception of 2 streams in the current trial increased with greater frequency separation between the A and B tones (⌬ f). Larger ⌬ f in previous trials modified this pattern, causing less streaming in the current trial. This occurred even when listeners were asked to bias their perception toward hearing 1 stream or 2 streams. The effect of previous ⌬ f was not due to response bias because simply perceiving 2 streams in the previous trial did not cause less streaming in the current trial. Finally, the effect of previous ⌬ f was diminished, though still present, when the silent duration between trials was increased to 5.76 s. The time course of this context effect on streaming implicates the involvement of auditory sensory memory or neural adaptation.