Date of Award

1993

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Communication Sciences and Disorders

First Advisor

M. Jane Collins

Abstract

Auditory scene analysis refers to the process through which sounds are heard as either belonging to separate sources or as perceptually grouped together and arising from a single source. Stream segregation describes the perceptual separation of sounds, while sequential integration is a term used to describe the linking together of sounds following one another in time. This study examined the minimum duration necessary for the perception of sequentially-presented sounds to change from sequential integration to stream segregation. The experimental stimuli were sequences of alternating sounds. Auditory scene analysis was examined under conditions in which the sequential sounds differed only in frequency (pure-tone sounds) or center frequency (amplitude-modulated noise-bands). Other experimental conditions were included in which the alternating sounds differed also in intensity (pure-tone sounds) or temporal envelope (amplitude-modulated noise-bands). This study revealed that stream segregation was increased by increasing the duration of the sequences. Frequency separation also had a significant effect on auditory scene analysis. Larger frequency separations led to more rapid stream segregation. Additionally, less segregation was observed for the amplitude-modulated sounds with similar temporal envelopes. Finally, the results indicated that intensity difference and envelope similarity were not processed independently of the frequency separations used in this study.

Pages

103

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