Nan Xu, Denis Burnham, MARCS Auditory Laboratories, University of Western Sydney
Vowel hyperarticulation in infant-directed speech (IDS) has been found consistently across both tone (Mandarin ) and non-tone (Russian, Swedish, American  and Australian English ) languages and has been posited as a possible bootstrapping mechanism for early language development in infancy . Here we investigated (1) IDS in Cantonese to examine whether tones, like vowels, are hyperarticulated in a tone language and (2) the interaction of F0 measures (mean and range) in tone and intonation. Our results show there is tone hyperarticulation in Cantonese IDS compared to Cantonese adult-directed speech (ADS). Regarding the interaction of tone and intonation, F0 mean was elevated in IDS compared with ADS especially for level tones. F0 range is greater in intonation over utterances than in tones in words, and greater in ADS than IDS. These results suggest that pitch in IDS tone hyperarticulation and IDS intonation is manipulated relatively independently and tone fidelity is not affected by the exaggerated intonation of IDS.