The current study examines how bidialectalism influences non-native speech production. We compared monodialectal Mandarin Chinese with bidialectal Shanghai-Mandarin Chinese speakers in terms of their ability to produce easy and difficult American English vowels. The results showed a general advantage for the bidialectal group compared with the monodialectal group in the production of the vowel formants and duration of the easy English vowels [i] and [u]. However, for the English vowels [ɪ] and [ʊ] known to be difficult for Chinese learners of English, both groups experienced the same challenges in terms of accurately producing the formants of the target vowels. Nevertheless, the bidialectal Shanghai-Mandarin speakers were still better than the monodialectal Mandarin speakers in the durational aspect of the two difficult English vowels. The results are explained by the Second Language Linguistic Perception (L2LP) model and suggest that the bidialectal advantage in non-native speech acquisition is subject to the modulation of cross-linguistic difficulty of the target speech sounds.
