Scrutinizing the role of length of residence and age of acquisition in the interlanguage pronunciation development of English /ɹ/ by late Japanese bilinguals

Abstract

The current project examined whether and to what degree continued L2 input, operationalized as length of residence (LOR), and age of acquisition (AOA), defined as the first intensive exposure to the target language, can be predictive of adult Japanese learners’ production of word-initial English /ɹ/. Data were collected from 65 participants, consisting of three groups of Japanese learners of English (n = 13 for Short-, Mid-, and Long-LOR groups, respectively) and two groups of baseline speakers (n = 13 for Japanese- and English-Baseline groups, respectively). Their production of /ɹ/ was elicited via three oral tasks (i.e., word reading, sentence reading, timed picture description). Acoustic analyses were carried out along four dimensions: third formant (F3), second formant (F2), first formant (F1) frequencies, and formant transition duration. The results demonstrated that (a) all learners reached native-like proficiency with respect to the use of existing cues (F2, transition duration) within approximately one year of LOR, (b) their performance was negatively related to AOA to some degree, and (c) longer LOR was predictive of the development of the new cue (F3). These results suggest that late L2 speech sound acquisition and proficiency may be characterized by different levels of phonetic processing.