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

Abstract

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 specificto 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.