Proficient bilingual listening requires differential processing of sound variation in each language context. We consid-ered context-based processing of pitch information by Mandarin-English bilinguals, for whom pitch indicates word distinctionsin one language but not the other. In an eye-tracked word-learning experiment, 58 bilinguals and 28 English monolinguals eachlearned English-like and Mandarin-like wordsets, words referring to images. Wordsets differed primarily in that English-likewords contained final consonants. We explained that some words might differ only in their pitch patterns, and included train-ing on minimal tone pairs. In test, two pictures appeared on the screen with referents differing in either tone or vowel. Onepicture was labeled. Bilinguals processed tones more efficiently (t(78) = 3.54, p = .001) and more accurately (t(84) = 3.78, p <.001) than monolinguals only in the Mandarin context. Mandarin-English bilinguals thus appear to tailor tone processing to thewithin-word language context.

This article reviews research on when acoustic-phonetic variability facilitates, inhibits, or does not impact perceptual development for spoken language, to illuminate mechanisms by which variability aids learning of language sound patterns. We first summarize structures and sources of variability. We next present proposed mechanisms to account for how and why variability impacts learning. Finally, we review effects of variability in the domains of speech-sound category and pattern learning; word-form recognition and word learning; and accent processing. Variability can be helpful, harmful, or neutral depending on the learner's age and learning objective. Irrelevant variability can facilitate children's learning, particularly for early learning of words and phonotactic rules. For speech-sound change detection and word-form recognition, children seem either unaffected or impaired by irrelevant variability. At the same time, inclusion of variability in training can aid generalization. Variability between accents may slow learning-but with the longer-term benefits of improved comprehension of multiple accents. By highlighting accent as a form of acoustic-phonetic variability and considering impacts of dialect prestige on children's learning, we hope to contribute to a better understanding of how exposure to multiple accents impacts language development and may have implications for literacy development. This article is categorized under: Linguistics > Language Acquisition Psychology > Language Psychology > Perception and Psychophysics.

Much research focuses on speech processing in infancy, sometimes generating the impression that speech-sound categories do not develop further. Yet other studies suggest substantial plasticity throughout mid-childhood. Differences between infant versus child and adult experimental methods currently obscure how language processing changes across childhood, calling for approaches that span development.

Purpose

The purpose of this study was to determine whether the degree of dominance of Mandarin-English bilinguals' languages affects phonetic processing of tone content in their native language, Mandarin.

Method

We tested 72 Mandarin-English bilingual college students with a range of language-dominance profiles in the 2 languages and ages of acquisition of English. Participants viewed 2 photographs at a time while hearing a familiar Mandarin word referring to 1 photograph. The names of the 2 photographs diverged in tone, vowels, or both. Word recognition was evaluated using clicking accuracy, reaction times, and an online recognition measure (gaze) and was compared in the 3 conditions.

Results

Relative proficiency in English was correlated with reduced word recognition success in tone-disambiguated trials, but not in vowel-disambiguated trials, across all 3 dependent measures. This selective attrition for tone content emerged even though all bilinguals had learned Mandarin from birth. Lengthy experience with English thus weakened tone use.

Conclusions

This finding has implications for the question of the extent to which bilinguals' 2 phonetic systems interact. It suggests that bilinguals may not process pitch information language-specifically and that processing strategies from the dominant language may affect phonetic processing in the nondominant language-even when the latter was learned natively.

Previous research has mainly considered the impact of tone-language experience on ability to discriminate linguistic pitch, but proficient bilingual listening requires differential processing of sound variation in each language context. Here, we ask whether Mandarin-English bilinguals, for whom pitch indicates word distinctions in one language but not the other, can process pitch differently in a Mandarin context vs. an English context. Across three eye-tracked word-learning experiments, results indicated that tone-intonation bilinguals process tone in accordance with the language context. In Experiment 1, 51 Mandarin-English bilinguals and 26 English speakers without tone experience were taught Mandarin-compatible novel words with tones. Mandarin-English bilinguals out-performed English speakers, and, for bilinguals, overall accuracy was correlated with Mandarin dominance. Experiment 2 taught 24 Mandarin-English bilinguals and 25 English speakers novel words with Mandarin-like tones, but English-like phonemes and phonotactics. The Mandarin-dominance advantages observed in Experiment 1 disappeared when words were English-like. Experiment 3 contrasted Mandarin-like vs. English-like words in a within-subjects design, providing even stronger evidence that bilinguals can process tone language-specifically. Bilinguals (N = 58), regardless of language dominance, attended more to tone than English speakers without Mandarin experience (N = 28), but only when words were Mandarin-like-not when they were English-like. Mandarin-English bilinguals thus tailor tone processing to the within-word language context.