Effects of consonant-conditioned informativity on vowel duration in Japanese

Research on English and other languages has shown that syllables and words that contain more information tend to be produced with longer duration (e.g. Aylett & Turk 2004). This research is evolving into a general thesis that speakers articulate linguistic units with more information more robustly. While this hypothesis seems plausible from the perspective of communicative efficiency, previous support for it has come mainly from English and some other Indo-European languages. Moreover, most previous studies tended to focus on rather global effects, such as the interaction of word duration and sentential/semantic predictability, but we feel that it is also essential to explore a more local interaction between adjacent segments, where meaning is irrelevant. With these two issues in mind, the current study examines the effects of local informativity on vowel duration in Japanese, using the Corpus of Spontaneous Japanese (the CSJ). To examine consonantvowel phonotactics within a CV-mora, consonant-conditioned Shannon entropies were calculated, and their effects on vowel duration were examined, together with other linguistic factors that are known from previous research to affect vowel duration. In addition to confirming several linguistic factors affecting vowel duration, the current study reveals rather complex effects of consonantconditioned entropy on vowel duration in Japanese.