Effects of learning English as a second language on the acquisition of a new phonemic contrast

Abstract

Very sharp discrimination functions for the timing of voice onset relative to stop release characterize perceptual boundaries between certain pairs of stop consonants for adult speakers of many languages. To explore how these discriminations depend on experience, we studied their development among Kikuyu children, whose native language contains no stops in which voicing is subtantially delayed relative to stop release (e.g., /p/). Kikuyu distinguishes stops in which voice onset substantially precedes release (prevoiced) from those in which voice onset is nearly simultaneous with release (voiced) for apical and velar places of articulation. However, the language has only a single prevoiced labial stop. Prior to exposure to English, children discriminated prevoiced from voiced labials and voiced from voiceless labials, although these distinctions are not phonemic in Kikuyu. Moreover, the voiced/voiceless discrimination for labials ([ba] versus [pa]) improved markedly with schooling in English, rapidly surpassing the prevoiced/voiced distinction. Apparently, certain voice onset time differences are naturally discriminable, but it is also apparent that the very fine voiced/voiceless discrimination among adults for whom it is phonemic is largely attributable to experience.