Developmental change in English stress manifestation by Japanese speakers

This study investigated the developmental change in the phonetic realization of English stress, using corpus data of Japanese English learners with varying proficiency. Previous studies demonstrated that highly proficient Japanese learners of English can produce native-like English lexical stress in terms of intensity, F0, and vowel duration, but not vowel quality. The results of our study showed that the contrasts in intensity, F0 and duration were manifested by all proficiency groups while spectral contrast was consistently absent. In addition, significant differences in vowel duration were found between native speakers and Japanese speakers of low-to-medium English proficiency level. The results imply that Japanese mora-timed rhythm is an obstacle in manifesting native-like lexical stress. These two findings suggest that it is more difficult to overcome L1 interference of segmental phonology than of suprasegmental phonology.