Phonetic evidence for early language differentiation: Research issues and some preliminary data

Although evidence is now available from several domains of language acquisition research that bilingual (BFLA) children differentiate their languages from the time of their earliest productions, studies in the phonetics-phonology domain have been sparse until recently. In this paper we first highlight some methodological issues that impact phonetic phonological data collection and interpretation. These issues include language context, bilingual versus monolingual mode, and adult listening bias. After suggesting types of acoustic evidence that can be used to determine whether the phonological modules of a young bilingual child are separate, we focus on voice onset time (VOT). We discuss methodological issues specific to a VOT study, including segmental context, rate of speech, and the position of word stress. We also present preliminary data from two BFLA children, ages four and two, learning Japanese and English. Separate recordings were made of the two children as they were asked to identify various pictures. Each child’s VOTs were calculated and compared across languages. Results showed that the two-year-old had no significant difference between languages. However, the t-test results for the four-year-old indicated that, for /p/ and /t/, VOT for English was of significantly longer duration than VOT for Japanese. 1The state of the art We can now hypothesize with some confidence that children raised bilingually from birth1 realize from the beginning that they are learning more than one language, and their language representations, constraints, and rules are in keeping with this recognition. Evidence is now available from several domains of language acquisition research that bilingual (BFLA) children need not go through a stage in which they have a single representation system for their two input languages (Genesee’s, 1989, Unitary Language System hypothesis) but rather differentiate their languages from the time of their earliest productions.2 By early 271 Early language differentiation: Phonetic evidence The International Journal of Bilingualism Address for correspondence Volume 6 • N mber 3 • September 2002, 271– 289 Carolyn Johnson, School of Audiology and Speech Sciences, University of British Columbia, 5804 Fairview Avenue, Vancouver, B.C. V6T 1Z3, Canada; e-mail: < [email protected]>.