Phrase-final lengthening and stress-timed shortening effects in native speakers and Japanese learners of English

Abstract

This study analyzes the durational patterns of native Japanese speakers learning English, with a focus on the two major prosodic effects: phrase-final lengthening and stress-timed shortening. To investigate the significance of these effects, a production experiment was conducted, adapting the method of Beckman and Edwards [Papers in Laboratory Phonology I, 152–178 (1990)]. Native speakers, beginning Japanese learners, and advanced Japanese learners of English were compared. Results are as follows: (1) The phrase-final lengthening effect is large and the stress-timed shortening effect is small in the speech of the native English speakers and the advanced Japanese learners; (2) all Japanese speakers are more successful in applying phrase-final lengthening before larger prosodic boundaries than before smaller ones. Further analysis shows that the native English speakers make more durational contrast between lexically stressed and unstressed syllables (this is called localcontrast) and also differentiate the three degrees of boundary strength hierarchically (this is called hierarchicalcontrast). These two types of durational contrasts are considered to be effective benchmarks to assess the acquisition of English stress-timing by Japanese learners, due to their considerable correlation with learner proficiency levels.