Learning to Accommodate Variation in Speech Input

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To become fluent native speakers and listeners, children ultimately must perceive and produce speech that is consistent with the local dialect. For example, English spoken in Calgary, Canada sounds slightly different than English spoken in Pittsburgh, Pennsylvania. The variation in these two English environments is patterned and, in learning language, children must acquire these regularities. Seemingly at odds with this, children must also maintain some flexibility in mapping speech sounds to meaning. For example, infants sometimes encounter talkers whose speech deviates quite drastically from their community's dialectal norms, as when addressed in English by a non-native speaker from Italy. Thus, while learning the normative patterns of their local dialect, children also must maintain enough cognitive flexibility to accommodate talkers who do not fall within these norms. How do infants and toddlers accomplish these seemingly competing tasks in language learning? Answering this question will reveal general characteristics of children's learning at multiple time scales: from spontaneous interpretation of fleeting speech sounds, to short-term adaptation to deviations from expectation, to longer-term learning of the regularities of the local dialect. This research maps the range of acoustic variability to which infants are exposed in their native speech environment in different social interactions with adults. It will create a detailed acoustic speech production corpus with which to understand the challenges confronting infant language learners. The research will also study how infants' and toddlers' speech perception is shaped by regularities of the local dialect, revealing the mechanisms of long-term sensitivity to dialect norms and short-term adaptation to deviations from dialect norms. It will also investigate how toddlers' growing vocabularies influence adaptation to variability in spoken language.The research takes an innovative cross-disciplinary approach to these questions. Understanding early development of the knowledge of the sound structure of English and its interaction with developing vocabularies will contribute to our understanding of typical language development. It will also further our understanding of accent development in multilingual learning situations and early communicative deficits. An important outcome of the project will be the dissemination of a speech corpus, providing a rich acoustic sample of speech for other researchers to use in studying English dialects.