Cross-language differences of articulation rate and its transfer into Japanese as a second language.

Recently, the articulation rate has been attracting attention in forensic speech investigation as an acoustic feature that varies across speakers, dialects, and languages. The present study investigates how cross-language differences in the articulation rate are transferred into Japanese as a second language. Participants were speakers of Japanese, Chinese, Korean, and Thai. They were recorded while they read a passage in their native language and in Japanese. Local and global articulation rates were calculated based on the number of syllables as well as the number of morae for Japanese speech. When we compared the articulation rate of the native languages, Japanese was the fastest, then Korean, Chinese, and Thai in that order. Also, a significant positive correlation was observed between the articulation rate of the native language and that of the second language. A gender difference was found in the articulation rate of some languages, with males speaking faster than females. The effect of age was limited to Thai speakers only. Accent discrimination and identification experiments were conducted and the results revealed that native and non-native accents could be correctly discriminated just by the articulation rate.