English L2 Vowel Acquisition over Seven Years

Although cross-sectional research designs have been widely used in the evaluation of L2 phonetic learning, longitudinal studies of L2 speech production are rare. As a result, it is difficult to draw strong conclusions about the effects of language experience on L2 phonetic acquisition. This investigation of adult Slavic (Russian and Ukrainian) and Mandarin speakers tracks their English high vowel productions during seven years of residence in an English-speaking area. At the outset of the study, all participants had limited English oral proficiency. To evaluate phonetic learning, recordings of English vowels produced in controlled phonetic contexts were compared at the outset of the study, at one year, and at seven years. Vowel intelligibility was assessed through listener judgments in a blind identification task, and vowel accuracy was evaluated through acoustic measurements. While the results support the proposal that adults remain open to phonetic learning, they also indicate a dramatic slowing of the acquisition process by the end of the first year.