The use of tonal coarticulation in segmentation of artificial language speech: A study with Mandarin listeners

Zhe-Chen Guo,Shu-Chen Ou

doi:10.1017/s0142716420000818

Abstract

AbstractTonal carryover assimilation, whereby a tone is assimilated to the preceding one, is conditioned by prosodic boundaries in a way suggesting that its presence may signal continuity or lack of a boundary. Its possibility as a speech segmentation cue was investigated in two artificial language (AL) learning experiments. Mandarin-speaking listeners identified the “words” of a three-tone AL (e.g., [pé.tī.kù]) after listening to six long speech streams in which the words were repeated continuously without pauses. The first experiment revealed that segmentation was disrupted in an “incongruent-cues” condition where tonal carryover assimilation occurred across AL word boundaries and conflicted with statistical regularities in the speech streams. Segmentation was neither facilitated nor inhibited in a “congruent-cues” condition where tonal carryover assimilation occurred only within the AL words in 27% of the repetitions and never across word boundaries. A null effect was again found for the congruent-cues condition of the second experiment, where all AL word repetitions carried tonal carryover assimilation. These findings show that tonal carryover assimilation is exploited to resolve segmentation problems when cues conflict. Its null effect in the congruent-cues conditions might be linked to cue redundancy and suggest that it is weighted low in the segmentation cue hierarchy.

Highlights

A crucial mental process during spoken language comprehension is the segmentation of continuous speech streams into discrete units such as words
To extend this line of work, we examined the effect of tonal carryover assimilation, a cross-linguistically attested type of tonal coarticulation, on Mandarin listeners’ segmentation with two artificial language (AL) learning experiments
Experiments 1 and 2 found that their segmentation performance was hampered in the incongruent-cues conditions, suggesting that the tonal carryover assimilation cue was exploited despite its conflict with transitional probability (TP)

Summary

Introduction

A crucial mental process during spoken language comprehension is the segmentation of continuous speech streams into discrete units such as words. Accumulated evidence has demonstrated that listeners exploit a wide variety of cues to facilitate this process (see, e.g., Cutler, 2012; Davis, Marslen-Wilson, & Gaskell, 2002, for reviews) These range from statistical regularities in the speech input to language-specific phonological patterns and acoustic-phonetic details. Adjacent segments are more strongly coarticulated within words than between words (Byrd, 1996; Byrd & Saltzman, 1998), or across a smaller prosodic boundary than across a larger one (Cho, 2004; Fougeron & Keating, 1997) Listeners can use such coarticulatory information to segment speech (Fernandes, Kolinsky, & Ventura, 2010; Fernandes, Ventura, & Kolinsky, 2007)

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