Acoustic manifestations of mora timing in Japanese

Abstract

Segment durations in 20 minimal-paired words in Japanese were examined to identify regular patterns of acoustic manifestations of mora timing in Japanese. The results indicate that segments consistently stretch or compress, providing temporal compensation within a mora and between moras, to attain targeted length at the word level. A segment is 11% longer in the pre-geminate-stop position than in the pre-single-stop position; in the word final position, a segment is 9% shorter following a geminate stop than a segment following a single stop; and [t] in the same phonotactic environment shows varied durations according to different moraic conditions. Fricatives followed by a devoiced vowel are considerably longer than any other inherently long, nonmoraic segments, and are comparable to moraic segments and the average mora duration. Syllable durations are not isochronous, varying by as much as 50%. The word duration is affected more by the number of component sounds and their inherent durations in two-mora than in three-or four-mora words. When the word durations are converted into ratios, they are markedly similar to the mora values. The results suggest a timing control mechanism adjusting segments to obtain targeted word durations. These phenomena describe mora timing in Japanese.