Yuan Zhao (colloquium abstract)

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The Role of Probability in the Production and Learning of Lexical Tone Categories

Yuan Zhao
Stanford University

ABSTRACT

Frequency-based probabilistic knowledge has been shown to affect various aspects of segmental production and processing. For instance, high-frequency words are produced with more lenited phonetic forms than low-frequency words (e.g. Bybee, 1996, 2000; Jurafsky, et al. 2003); sound sequences of high probability are processed faster than those of low probability (Vitevitch & Luce, 1998, 1999; Goldrick & Larson, 2008). Is probabilistic knowledge an essential part of linguistic knowledge? If so, its influence should extend to suprasegmental events as well, such as lexical tones. In this talk, through a production experiment and two learning experiments, I show that probabilities, as estimated from relative frequency, affects tone hyperarticulation and tonal category learning. Specifically, the results suggest that in tone production, frequency targets the phonemic contrast of the tones, while a comparable non-linguistic source of hyperarticulation, Lombard speech under noise, does not affect tone distinctiveness. In learning, learners are extremely sensitive to the token frequency of tone exemplars and are able to successfully capitalize on the frequency cues via a Bayesian process.