Speaker and rate normalization in the perception of lexical tone by Mandarin and English listeners.

摘要

This thesis examines the influence of contextual acoustic information on the perception of Mandarin Chinese tones, through an investigation of speaker and rate normalization. The research constitutes new evidence concerning the role of contextual acoustic information in tone perception, normalization in suprasegmentals, and the influence of language experience on normalization.; The study investigates the hypothesis that listeners normalize for speaker pitch range and speaking rate in tone perception. Experiments examined whether identical tone stimuli were identified differently depending on speaker F0 (fundamental frequency) range or speaking rate information provided by a precursor phrase. The tone stimuli, synthesized Mandarin Chinese Tone 2-Tone 3 continua, varied in Turning Point (TP, the duration between the onset and inflection point of a tone), and {dollar}Delta{dollar}F0 (the difference in F0 between the onset and inflection point). Continua representing TP, {dollar}Delta{dollar}F0, or both acoustic dimensions were appended to precursor phrases representing high- and low-pitched speakers, and fast and slow speaking rates.; Results of both the speaker and speaking rate normalization experiments showed reliable shifts in identification as a function of the precursor. Normalization effects were observed only when both precursors and stimuli varied in the same acoustic dimension. Both speaker and rate effects diminished as stimuli more closely resembled natural speech.; Additional experiments compared perception of the same tone stimuli by native English speakers. In both the speaker and rate experiments, English listeners showed no effects in the single-cue continua, but showed effects for the TP/{dollar}Delta{dollar}F0 continuum. These results are consistent with the view that normalization is an obligatory, or auditory process. It is proposed that English listeners are only able to normalize when differences between target stimuli become perceptually salient. For Mandarin listeners, findings showed normalization effects for the single- and two-cue continua, demonstrating that language background influences normalization by enhancing phonemic judgments. This study affects theories of speech perception by providing evidence that normalization occurs in the absence of phonetic categories. The study also shows that temporal, as well as pitch properties, are robust acoustic cues in the perception of Mandarin tones.