Perceptual assimilation of Japanese vowels by American English listeners: effects of speaking style

Abstract

Our previous research on perceptual assimilation of non-native vowels to native categories showed that patterns of spectral and temporal assimilation vary with speaking style (citation vs sentence) and consonantal context. Japanese (J) listeners’ perceptual assimilation of American English (AE) long and short vowels to long (2-mora) and short (1-mora) categories was more consistent when the target syllables were presented in sentences (Strange, et al. ATR Technical Report, TR-H-218, 1997). In the present study, AE listeners categorized 4 speakers’ tokens of 10 J vowels /ii, i, ee, e, aa, a, oo, o, uu, u/ into 11 native AE categories and rated their goodness-of-fit on a 7-point scale (7 = native). Results indicated that patterns of temporal assimilation of the J short vowels /e, a, u/ differed with speaking style. Assimilation of /e/ to mid or high front spectral AE categories also varied with context and individual speakers. Goodness-of-fit ratings suggested that all 10 J vowels were considered relatively ‘‘good’’ instances of AE categories (medians = 5 to 7). In comparison with J listeners’ perception of AE vowels, AE listeners judged cross-language similarities between J and AE vowels more on the basis of their spectral characteristics than on their temporal characteristics.