Spatial Stream Segregation
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“Stream segregation” refers to a listener’s ability to disentangle interleaved sequences of sounds, such as the ability to string together syllables from one talker in the presence of competing talkers. Spatial separation of sound sources is a key factor that enables the task of segregation. Psychophysical tasks that require listeners to integrate sounds across locations demonstrate that listeners can overcome spatial separation of sources, suggesting that space is a relatively weak segregating factor. Contrary to that suggestion tasks that require listeners to isolate a sound sequence within a complex background demonstrate robust benefits of spatial separation of the target from other sources. This chapter reviews psychophysical studies that show weak versus strong spatial effects on streaming and shows that the spatial acuity of stream segregation can approach the limits of acuity of spatial hearing. Responses from auditory cortex in anesthetized animals are presented demonstrating that single neurons can exhibit spatial stream segregation by synchronizing selectively to one or the other of two interleaved sound sequences. The results from animals imply that perceptually segregated sound sequences are represented in auditory cortex by discrete mutually synchronized neural populations. Human magneto- and electroencephalographic results then are described showing selective enhancement of cortical responses to attended versus unattended sounds. Available results lead to a picture showing bottom-up segregation of sound sources by brainstem mechanisms on the basis of spatial and other cues, followed by top-down selection of particular neural populations that could underlie perceptual auditory objects of attention.
KeywordsAuditory cortex Rhythmic masking release Scene analysis Spatial hearing Spatial streaming Stream integration Spatial release from masking
I thank Georg Klump, Lauren Javier, and Justin Yao for their helpful suggestions on the manuscript. This chapter was completed while the author was a resident fellow at the Hanse-Wissenschaftskolleg in Delmenhorst, Germany. The author’s work is supported by the National Institutes of Health grant R01 DC000420.
Compliance with Ethics Requirements
John Middlebrooks has no conflicts of interest.
- Bregman, A. S. (1990). Auditory scene analysis: The perceptual organization of sound. Cambridge, MA: MIT Press.Google Scholar
- Edmonds, B. A., & Culling, J. F. (2005a). The role of head-related time and level cues in the unmasking of speech in noise and competing speech. Acta Acustica united with Acustica, 91, 546–553.Google Scholar
- Moore, B. C. J., & Gockel, H. (2002). Factors influencing sequential stream segregation. Acta Acustica, 88, 320–332.Google Scholar
- Stein, B. E., & Meredith, M. A. (1993). The merging of the senses., Cognitive Neuroscience Series Cambridge, MA: MIT Press.Google Scholar
- van Noorden, L. P. A. S. (1975). Temporal coherence in the perception of tone sequences. PhD dissertation, Eindhoven: University of Technology.Google Scholar