Miyoko Sugito (Institute for Speech Communication Research): Devoiced Accented Vowels in Japanese

This paper discusses results of acoustic and physiological experiments on devoiced accented vowels in Osaka and Tokyo Japanese. Close vowels /u/ or /i/ between voiceless consonants are often devoiced in Japanese. In the Osaka dialect, when open vowels follow the voiceless consonants like /kusa/ "grass" or /kita/ "north" etc., they have pitch accent on the first mora, even when they are devoiced. Devoiced accented vowels are also found in speech of the Tokyo dialect. The first vowels being devoiced or not are related to the rate of speech. Accent was found to shift to the second vowel in very fast speech of both dialect speakers. The falling F0 contours on the following second vowel result in perception of High-Low accent, whether the preceding vowel is voiced or devoiced. The temporal variations in pitch movements are primarily controlled by the laryngeal muscles. The patterns of laryngeal activity of the word with devoiced accented vowels are very similar to those for voiced /kusa/ in the Osaka dialect, with a peak of CT (crycothyroid muscle) activity associated with the first vowel, and SH (sternohyoid muscle) activity associated with fall of the final F0 fall of the second vowel. It is notable that the CT activity is found at the time it would occur if the vowel were voiced, just as observed for voiced /kusa/. However, when the word is pronounced very fast, the CT activity on the devoiced accented vowel may not be in time to produce a pitch accent on the first vowel. Instead, in very fast speech in both dialects, there may be a shift of accent to the second fast vowel.