Third International Conference on Spoken Language Processing (ICSLP 94)
This study examines the naturalness threshold of English stressed vowels for Americans and Japanese learners of English. Conversely, the naturalness threshold of Japanese accented vowels for Japanese speakers is compared to that of Japanese for American learners. Perception experiments demonstrated Americans are more sensitive to the shortening of a vowel both in English and Japanese than Japanese. As for the lengthening of a vowel, Japanese learners of English were found to be less tolerant of lengthening in English vowels. Likewise, in Japanese stimuli, the Japanese were less tolerant of lengthening than the Americans when a vowel was followed by a voiced consonant. In Japanese vowels followed by either a voiceless consonant or a flap, the Japanese were conversely more tolerant of lengthening than the Americans. We found certain factors, such as the phonemic vowel length distinction and a voice-conditioned effect, which exerted an influence on these judgments of naturalness.
Bibliographic reference. Mochizuki-Sudo, Michiko / Kiritani, Shigeru (1994): "Naturalness judgments for stressed vowel duration in second language acquisition", In ICSLP-1994, 1719-1722.