The current project studied speech rhythm of L2 English produced by native Japanese speakers. Among various factors of English speech rhythm, the study focused on vowel epenthesis that seems to severely impede accurate manifestation of it.

    Vowel epenthesis by native Japanese speakers has been extensively studied in terms of the articulatory problem and L1 phonological transfer. However, it has not so much been studied in relation to speech rhythm.

    Using 72 read speech data of The North Wind and the Sun in J-AESOP corpus, duration of epenthetic vowels was analysed for both beginner and advanced Japanese learners of English.

    The result first showed that the advanced speakers produced shorter epenthetic vowels than beginner speakers, suggesting that advanced speakers’ English has better rhythm. However, when we took into consideration the speech rate, which was also shorter for advanced speakers, the statistically significant difference was not observed.

    Therefore, unlike the results of the previous studies about English reduced vowels, which are shorter for advanced learners of English, the result of the current study shows that the developmental change in vowel epenthesis by native Japanese speakers is on its frequency (less for advanced learners) but not on its realisation.