Early and Late Spanish-English Bilingual Adults' Perception of American English Vowels

Increasing numbers of Hispanic immigrants are entering the US (US Census Bureau, 2011) and are learning American English (AE) as a second language (L2). Many may experience difficulty in understanding AE. Accurate perception of AE vowels is important because vowels carry a large part of the speech signal (Kewley-Port, Burkle, & Lee, 2007). The relationship between native language and L2 vowel inventories causes some vowels to be more difficult to perceive accurately than others (Best & Tyler, 2007). The present study examined the patterns with which early and late Spanish-English bilingual adults assimilate AE vowels to their native vowel inventory and the accuracy with which they discriminate and identify the vowels. Early bilingual listeners demonstrated similar perceptual assimilation patterns to late bilingual listeners, but judged AE vowels as less Spanish sounding than did late learners. Additionally, discrimination and identification accuracy of L2 vowels improved with early age of L2 acquisition. However, early bilingual listeners’ vowel perception was not native-like. Certain AE vowels (/ʌ/, /ɑ/ and /æ/) were difficult to discriminate and identify. Perceptual assimilation patterns predicted categorial discrimination accuracy, an outcome posited by the Perceptual Assimilation Model-L2 (Best & Tyler, 1997)