Transfer of Incomplete Neutralization: A Case of /ei/ and /ou/ in Japanese

Abstract

This study examined whether phonological neutralization in L1 Japanese, where the vowel sequences /ei/ and /ee/ are claimed to be incompletely neutralized to [eː] while /ou/ and /oo/ to be more completely neutralized to [oː], would transfer to the production of L2 English diphthongal vowels /eɪ/ and /oʊ/. Data were obtained from 100 Japanese learners of English in the J-AESOP corpus, which includes their oral proficiency judgments by trained phoneticians. Acoustic and statistical analysis revealed that low-proficient Japanese learners of English produced both /eɪ/ and /oʊ/ with significantly smaller formant changes than native English speakers. More proficient learners produced /eɪ/ with near-native formant changes, but their production of /oʊ/ was still significantly different from native production. Based on the results, it is argued that: (1) Japanese speakers tend to produce English /eɪ/ and /oʊ/ as monophthongal [eː] and [oː] due to the transfer of phonological neutralization, and (2) the acquisition of diphthongal /oʊ/ is more difficult than that of /eɪ/ because the transferred /ou/-/oo/ neutralization is more complete than the /ei/-/ee/ neutralization. The nearly complete neutralization of /ou/ and /oo/ may also explain why Japanese speakers often confuse English /oʊ/ and /ɔː/ (e.g., boat vs. bought).