英語学習者発話データに見る語末の延伸母音挿入

Vowel epenthesis, or insertion of vowels where they shouldn't be pronounced, are among the frequent errors that Japanese learners of English make when they speak English. Based on the data that we collected in what we call "oral response practices" conducted in freshmen English classes, we observe a related but slightly different phenomenon, namely prolonging of vowels, or insertion and prolonging of vowels, at the end of words that occur in the course of relatively spontaneous speech by college learners of English in Japan. Based on audio recordings and transcriptions of face-to-face interactions, we investigate the conditions under which such prolongations of word-final vowels may occur in actual learners' speech, more specifically, (1) whether it tends to occur more frequently in reading aloud written texts or in spontaneous utterances and (2) what kinds of word tends be involved in this process and explore possible explanations for these.