Auditory streaming is cumulative.

Abstract

The auditory system appears to begin listening to an input with a bias toward hearing the input as a single stream, but it gradually accumulates evidence over a period of seconds which may lead to the input's being split into substreams. Several seconds of silence or of unpatterned noise slowly remove the bias of the mechanism in favor of these streams. These effects were demonstrated in experiments in which young adult listeners sped up sequences of tones until they split. The sequences varied in the number of tones packaged between recurrent "separators" (periods of silence or of white noise) and in the lengths of these separators.If a sequence of tones of different pitches is played rapidly enough, it seems to split perceptually into two or more concurrent substreams. Subgroups of tones closely related in frequency, or following a smooth trajectory in frequency, will form part of the same stream. The splitting increases when the subgroups are farther away in frequency or when the sequence is played faster (Bregman & Campbell, 1971;Heise & Miller, 1951;Miller & Heise, 1950; Van Noorden, Note 1). The splitting phenomenon may also be observed with repeating short cycles of speech sounds (Cole & Scott, 1973;Dorman, Cutting, & Raphael, 1975;Lackner & Goldstein, 1974).These effects are seen by the author (Bregman, 1978b; Bregman & Dannenbring, in press) as the product of an auditory "parsing" mechanism. In natural environments, the sounds emitted by different sources reach our ears, mixed together. The auditory system must group the acoustic

Objective and Subjective Psychophysical Measures of Auditory Stream Integration and Segregation

“…This suggests that when listeners were actively trying to segregate sounds in the current study, stream segregation occurred almost instantaneously after the start of the stimulus sequence. Under these conditions, the segregation "build-up" effect, which has been observed in other studies under neutral listening conditions (van Noorden 1975;Bregman 1978;Anstis and Saida 1985;Carlyon et al 2001;Cusack et al 2004;Micheyl et al 2005a;Pressnitzer et al 2008) and conditions that encouraged integration (Roberts et al 2008), appears to have. However, the lack of a significant effect of N in this experiment should not be interpreted as evidence that build-up effects cannot be obtained under conditions that promote stream segregation.…”

“…Finally, based on the results of earlier studies, which showed that stream segregation usually "builds up" over time (van Noorden 1975;Bregman 1978;Anstis and Saida 1985;Carlyon et al 2001;Cusack et al 2004;Micheyl et al 2005a;Pressnitzer et al 2008), we expected the proportion of "two streams" responses to increase as a function of sequence length. Instead, relatively large proportions of "two streams" responses were observed in response to short stimulus sequences that contained only two triplets, as long as the frequency separation was relatively large.…”

“…The tone repetition rate, or the inter-tone interval, and the number of tones in the sequence also play an important role. In general, faster presentation rates, or shorter tone intervals, and longer sequence lengths promote segregation (van Noorden 1975;Bregman 1978;Bregman et al 2000). Auditory streaming has been demonstrated using a variety of sounds, including pure tones, harmonic complex tones (Cusack and Roberts 1999;Grimault et al 2000Grimault et al , 2001Roberts et al 2002Roberts et al , 2008, synthetic vowels (Gaudrain et al 2007(Gaudrain et al , 2008, and noises (Bregman et al 2001;Grimault et al 2002), with streaming depending on differences in fundamental frequency (F0), spectral content, or temporal envelope modulation rate.…”

Properties of auditory stream formation

“…The build-up of stream segregation When a long sound sequence is presented with an intermediate difference between the sounds in the sequence, the tendency for fission to occur increases with increasing exposure time to the tone sequence [15,16]. One interpretation of this is that the auditory system starts with the assumption that there is a single sound source, and fission is perceived only when sufficient evidence has built up to contradict this assumption.…”

The initial phase of auditory and visual scene analysis

“…It is what allows us to follow a conversation in a crowded restaurant, in the midst of other conversations, with music in the background and the sound of tinkling glasses. An essential feature of streaming is that it takes time: initially, subjects tend to group all of the acoustic information into one global stream [2,3]. When we first walk into the restaurant, the first impression may be of a 'loud and undifferentiated noise' [4].…”