Cross-language speech perception in context : advantages for recent language learners and variation across language-specific acoustic cues

This dissertation explores the relationship between language experience and sensitivity to language-specific segmental cues by comparing cross-language speech perception in monolingual English listeners and Spanish-English bilinguals. The three studies in this project use a novel language categorization task to test language-segment associations in listeners’ first and second languages. Listener sensitivity is compared at two stages of development and across a variety of language backgrounds. These studies provide a more complete analysis of listeners’ language-specific phonological categories than offered in previous work by using word-length stimuli to evaluate segments in phonological contexts and by testing speech perception in listeners’ first language as well as their second language. The inclusion of bilingual children also allows connections to be drawn between previous work on infants’ perception of segments and the sensitivities of bilingual adults. In three experiments, participants categorized nonce words containing different classes of English- and Spanish-specific sounds as sounding more English-like or Spanish-like; target segments were either a phonemic cue, a cue for which there is no analogous sound in the other language, or a phonetic cue, a cue for which English and Spanish share the category but for which each language varies in its phonetic implementation. The results reveal a largely consistent categorization pattern across target segments. Listeners from all groups succeeded and struggled with the same subsets of language-specific segments. The same pattern of results held in a task where more time was given to make categorization decisions. Interestingly, for some segments the late bilinguals were significantly more accurate than monolingual and early bilingual listeners, and this was the case for the English phonemic cues. There were few differences in the sensitivity of monolinguals and early bilinguals to language-specific cues, suggesting that the early bilinguals’ exposure to Spanish did not fundamentally change their representations of English phonology, but neither did their proficiency in Spanish give them an advantage over monolinguals. The comparison of adult listeners with children indicates that the Spanish-speaking children who grow to be early bilingual adults categorize segments more accurately than monolinguals – a pattern that is neutralized in the adult results. These findings suggest that variation in listener sensitivity to language-specific cues is largely driven by inherent differences in the salience of the segments themselves. Listener language experience modulates the salience of some of these sounds, and these differences in cross-language speech perception may reflect how recently a language was learned and under what circumstances.