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The effects of noise on identification of topic changes in discourse

University of British Columbia

The purpose of the present study was to investigate how adverse listening conditions affect the ability of normal-hearing listeners to identify the boundaries between discourse topics, or when "what is being talked about" has changed. Twelve subjects (21 to 35 years) listened to digitized recordings of a single speaker's monologues presented in three background noise conditions (+5, 0 and -5 dB S:N). Subjects were asked to push a button when they thought that a change of topic was about to occur in the monologue. Subject responses were analyzed for the latency of topic boundary identification and the number and location of responses. The role of prosodic cues in the identification of topic boundaries was also evaluated. It was found that as the listening condition became less favourable, listeners were slower to identify topic boundaries, were less certain as to where topic boundaries occurred, and relied more heavily on cues to topic initiation than on cues to topic termination for identification of topic boundaries. It was also shown that as the signal-tonoise ratio decreased, listeners were less able to utilize cues to topic boundary that are present in low amplitude utterances such as pitch range and contour, laryngealization and pre-boundary syllable lengthening, but that listeners relied on the prosodic cue of pause duration to identify topic boundaries equally in all three listening conditions.

Thesis/Dissertation

application/pdf

2009-01-15

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http://hdl.handle.net/2429/3689

Audiology and Speech Sciences

University of British Columbia

UBCV

DSpace