A study of the production of unstressed vowels by Japanese speakers of English using the J-AESOP corpus

This study investigated the production of English unstressed vowels by Japanese speakers based on the J-AESOP corpus. Four acoustic features associated with unstressed vowels in English were examined: duration, intensity, fundamental frequency and vowel quality. Comparative analysis with native English speakers' production revealed that the Japanese speakers achieved good control of all the acoustic features except vowel quality, supporting the results of previous studies. Their attainment of nearnative control of duration, intensity and fundamental frequency can be attributed to positive L1 transfer from Japanese. As for vowel quality, the present study showed that the quality of the Japanese speakers' unstressed vowels was more peripheral than that of the native English speakers' because of the difficulty of L2 phoneme acquisition and the influence of orthography.