Liu, L. & Kager, R.
Utrecht Insititute of Linguistics - OTS, Utrecht University
Infants are born with an initial sensitivity to speech prosody, and undergo tonal perceptual reorganization (PR) between 4 and 9 months, after which non-tone-learning infants' sensitivity to tones sharply decreases. However, non-tone-language adults show a sharp psycho-acoustic sensitivity to linguistic pitch. A gap occurs regarding the transition from non-tone-language-learning infants' loss of tonal sensitivity to adults' recovery, calling for an inspection of the crucial periods in this perceptual change, and the factors that influence it. The research questions are: 1) When is the perceptual turning point for non-native pitch perception? 2) Do monolingual and bilingual infants follow the same tonal perceptual trajectory in this process? 3) Does the acoustic salience of the tonal contrast influence monolingual and bilingual infants' tone perception? 140 monolingual Dutch infants and 100 bilingual infants of five age groups (5 to 18 months) were tested on their discrimination of an acoustically salient tonal contrast (/ta/, high level vs. high falling) in Mandarin Chinese and a manipulated less-salient version of the same contrast differing solely on F0 direction. Results display a U-shaped pattern for bilingual infants by the end of the first year of life, and for monolingual infants at 17-18 months. In particular, bilingual infants follow the same developmental trajectory as their monolingual peers in tonal tuning (between 5 and 9 months), but recover their acoustic sensitivity earlier (at 11-12 months). To answer the research questions: The turning point for non-native pitch perception occurs early on in the first two years of life. Bilingual infants' enhanced sensitivity to non-native tonal contrasts at the end of the first year may be due to the more challenging language environment they encounter in general, and/or specifically regarding more complex intonation input. Acoustic salience influences both mono- and bilingual infants' perception, so that acoustically salient contrast may survive PR.