Analysis on the effects of tonal coarticulation at word and nonword syllable boundaries of Mandarin based on the tone nucleus model

As a typical tonal language, Mandarin has four lexical tone types, each of which has its own intrinsic pattern when uttered in isolation. However, when produced in context, the tonal contours present many variations, even if we specifically address the tone nucleus, which is defined as a stable part in a syllable. This study describes how and to what extent the word boundary affects tonal coarticulation in continuous speech. Although several previous works have investigated how the prosodic features of syllables are affected by their surrounding syllable tone types, most of them selected nonsense syllables uttered in a carrier sentence as study targets, which is far from natural situation. In this paper, after preparing a Mandarin speech corpus, in which all tone-type combinations of di-syllables are included with both intraword and interword cases, the degree of concatenation is compared for intraword and interword cases, viewing their tone component’s F0 means and ranges of tone nuclei. All target di-syllables are uttered in a phrase. Results indicate that the degree in the intraword and interword cases differ greatly depends on the tone combination. The results were applied into our tone component prediction system, which is based on the tone nucleus model.