Analysis and prediction of vowel devocalization in isolated Japanese words

Abstract

An analysis of vowel devocalization in Japanese is presented as an example to find general rules for allophonic variations of phonemes in continuous speech, i.e., to find quantitative relations between phoneme environments and allophonic variations. A speech database consisting of about 5000 common Japanese words spoken in isolation by a professional male announcer was used. The database used is part of a large scale speech database that is now being compiled and hand transcribed at several levels of phonetic detail. Based on the acoustic‐phonetic transcriptions of the speech data, factor analysis of the phonetic environment was performed for the devocalized vowels. The results reveal that the influence of the immediately following phoneme on devocalization is the greatest among the four factors examined. The second most important factor is the position of the accent nucleus. The automatic prediction of vowel devocalization is discussed using the results of this analysis.