The role of the listener's state in speech perception

Date of Completion

January 2009

Keywords

Language, Linguistics|Psychology, Cognitive

Degree

Ph.D.

Abstract

Accounts of speech perception disagree on whether listeners perceive the acoustic signal (Diehl, Lotto, & Holt, 2004) or the vocal tract gestures that produce the signal (e.g., Fowler, 1986). In this dissertation, I outline a research program using a phenomenon called perceptual compensation for coarticulation (Mann, 1980) to examine this question regarding objects of speech perception. In Experiments 1A, 1B and 2, I examine non-speech contexts and evaluate their implications for perceptual compensation. Results from these experiments support a masking account of non-speech effects, while challenging a spectral contrast account. I then investigate the role of listener's state of perceptual attunement on compensation for coarticulation. In Experiment 3, I use sinewave speech (Remez et al., 1981) as contexts. Results show that sinewave speech precursors produce boundary shifts and that these effects don't depend on whether listeners report hearing them as speech or non-speech. In Experiment 4, I evaluate whether these sinewave effects are caused due to spectral contrast or gestural attunement by temporally inverting the first two formants of the contexts, while leaving F3 unaltered. Listeners fail to show boundary shifts despite the F3 region (critical from a spectral contrast perspective) being left unaltered. Finally in Experiment 5, I examine whether listeners' own coarticulatory actions cause boundary shifts, in an effort to examine how general. No effects of listeners' actions were detected. In conclusion, I suggest a careful understanding of the perceptual and motor state of the listeners is imperative for a complete understanding of speech perception. ^

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