Distinctiveness and Assimilation in Vowel Perception in a Second Language.

Purpose The purpose of this study was to investigate how the distinctive establishment of 2nd language (L2) vowel categories (e.g., how distinctively an L2 vowel is established from nearby L2 vowels and from the native language counterpart in the 1st formant [F1] × 2nd formant [F2] vowel space) affected L2 vowel perception. Method Identification of 12 natural English monophthongs, and categorization and rating of synthetic English vowels /i/ and /ɪ/ in the F1 × F2 space were measured for Chinese-native (CN) and English-native (EN) listeners. CN listeners were also examined with categorization and rating of Chinese vowels in the F1 × F2 space. Results As expected, EN listeners significantly outperformed CN listeners in English vowel identification. Whereas EN listeners showed distinctive establishment of 2 English vowels, CN listeners had multiple patterns of L2 vowel establishment: both, 1, or neither established. Moreover, CN listeners' English vowel perception was significantly related to the perceptual distance between the English vowel and its Chinese counterpart, and the perceptual distance between the adjacent English vowels. Conclusions L2 vowel perception relied on listeners' capacity to distinctively establish L2 vowel categories that were distant from the nearby L2 vowels.