Speaker age effects on the voicing contrast of Tokyo Japanese stops

While older Japanese speakers from the Kansai region produce voiced-voiceless stop contrasts with a true voicing distinction, older speakers from the northern Tohoku region produce the same stop contrasts with a short- versus long-lag VOT distinction, similar to the voicing contrast of English stops. However, Japanese speakers of younger generations from both of these dialect regions have been observed to produce the voiced-voiceless stop contrast in much the same way to each other, and they also seem to be using VOT as a less informative cue for stop distinction than speakers of previous generations (Takada, 2011). This study investigates the status of this sound change in the speech from the Tokyo dialect region, generally considered the standard for the modern language. Using speech data available from the Corpus of Spontaneous Japanese, we analyze stops produced by Tokyo speakers to determine differences in voicing contrast conditioned by speaker age and gender. We expect the stop contrast of older speakers to pattern differently than that of younger speakers, and we expect to see evidence for a sound change in progress similar to that observed in the other dialects. We also explore other acoustic correlates that may potentially contribute to Japanese stop contrasts as the sound change progresses.