Development of tonal discrimination in young heritage speakers of Cantonese

This study uses the Perceptual Assimilation Model for Suprasegmentals (PAM-S) (So & Best, 2008, 2010), supported by the assumptions of the L2 Intonation Learning theory (LILt, Mennen, 2015), to investigate how young heritage speakers of Cantonese living in the United States acquired Cantonese tones. Sixty-seven heritage speakers, aged 5–11, were tested on their perception of Cantonese tonal contrasts using an ABX discrimination task. They were compared to 64 peers aged 5–12 in Hong Kong, where Cantonese is spoken as the majority language but English is also acquired from a young age. Two pairs of tones were tested: Tones 2 (mid rising) and 5 (low rising), which have similar pitch heights and contours, and Tones 1 (high level) and 4 (low falling), which have a larger phonetic contrast. As predicted, the heritage speakers were more accurate in discriminating between the more distinct pair of tones than between the more similar pair. They also scored lower than their peers from Hong Kong in both contrast conditions. Age of testing predicted accuracy for both groups, and Chinese literacy also had a significant effect for the heritage speakers. The potential lack of the Tone 2–5 contrast in the heritage speakers’ input is discussed as an explanation for these findings. This study illustrates the divergence in heritage speakers’ phonological development compared to majority language speakers, and shows the relevance of the PAM-S and LILt to the heritage language context.