Coarticulatory reinterpretation of allophonic variation: Corpus-based analysis of /z/ in spontaneous Japanese

In Standard Japanese, the phoneme /z/ is realized variably either as an affricate or a fricative. This variation was analyzed using a phonetically annotated part of the Corpus of Spontaneous Japanese. Contrary to the traditional linguistic account, the variation is not a positionally conditioned, hence categorical, allophonic variation. Although the effect of linguistic position exists to some extent, its influence is secondary compared to the influence of local temporal characteristics of speech called time allotted for consonant articulation (TACA). The overall prediction rate of the manner of /z/ articulation by means of TACA was 74%, and, when coupled with information on linguistic position, the prediction rate was as high as 80%.