Factors affecting utterance-final vowel devoicing in spontaneous Japanese

Investigation of spontaneous speech corpora has shown that vowel devoicing in Japanese is a statistical phenomena. However, factors behind vowel devoicing have not been fully studied. In addition, there have been no studies that specifically examined pre-pausal vowel devoicing. In this paper, we investigate vowel devoicing in the pre-pausal position, in particular, vowel devoicing occurring at the utterance-final position, using a corpus of spontaneous Japanese. We first show overall devoicing rates of morae appearing at the phrase-final, prepausal position, and illustrate that they are attributed to a small set of frequent lexical items. We then examine some factors that may affect the probability of vowel devoicing, focusing on some lexical items typically appearing at the utterance-final position. The results suggest that utterance-final vowel devoicing is influenced by final lengthening and the speaker’s cognitive load.