Identifying the presence of a code-switch: Evaluating the role of acoustic cues.

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Project Summary Many infants growing up in bilingual homes are regularly exposed to code-switching from their caregivers and other members of their community. Even parents who aim to use the “one -parent-one- language” method of bilingual language exposure tend to switch languages occasionally, producing sentences such as “Do you see the gato?”. In order to develop representations of each of their languages, which we know they do, infants must figure out not only that there are two languages in their environment, but at what point in a given sentence one language ends and the other one begins. Making this even harder, speakers often “blur” the distinction between languages by producing sounds in one language that are colored by the other (known as phonetic convergence). We kn ow that this convergence may help adult bilingual speakers to anticipate an upcoming code -switch. However, it is not clear whether it is present in speech to infant or if listeners who do not know the languages are sensitive to this cue. Aim 1 will test the extent to which Spanish-English bilingual parents produce cross- linguistic phonetic convergence when speaking to their infants and to a fellow adult. I will ask them to record narrations of wordless picture books in English, Spanish, and while switching between the two languages (Exp. 1) and will measure how acoustic-phonetic properties of their speech are modulated by the speech register and the presence and proximity of code-switching. Aim 2 focuses on the ability of listeners at several levels of language experience to detect code-switches when listening to unfamiliar languages. English monolingual (Exp. 2a) and Spanish-English bilingual (Exp. 2b) adults, and monolingual 5-to 14-month-old infants (Exp. 3) will listen to passages that switch between Mandarin and French and will identify the language they are hearing. I will test whether the presence of anticipatory phonetic convergence in voice-onset time and tone influences the speed at which listeners detect a language switch between these two rhythmically dissimilar languages. By assessing how these anticipatory phonetic cues influence the detection of code-switching in unfamiliar languages, we will be able to determine whether their importance to code-switching comprehension for fluent bilinguals is due to language-specific knowledge or is a result of general speech perceptual mechanisms. This project will also help us to better understand how infants exposed to code-switching are able to acquire two languages simultaneously. Having more evidence of the process infants undergo in order to solve this acquisition problem may help to provide more credibility to the suggestions we give to parents who wish to raise their children bilingually, as current advice reassures parents that their children can easily acquire multiple languages but does not detail how they can do that under different conditions.