The Production of Successive Addition Boundary Tone in Mandarin Preschoolers

In Mandarin Chinese, a falling tone or a rising tone can be added to the final lexical tone of an utterance, called successive addition boundary tone (SuABT). It can be used to convey pragmatic or paralinguistic information during conversation. Our primary concern is to understand how Mandarin-speaking children master the use of successive addition boundary tones (SuABT) during their interactive language development. In pursuit of this objective, the current study investigated the phonetic characteristics of falling SuABT produced by 25 preschoolers, ranging in age from 2;6 to 6;8, as well as their mothers who engaged in child-directed speech (CDS). Results showed that children as early as 2 years old were able to use falling SuABT to encode the phonological functions of tone and intonation simultaneously, however, the performance of SuABT production was tone-dependent. For children between 2–3 years old, errors were predominantly observed in the phonetic control of the lexical-tone part. Specifically, the pitch targets of tone 2 and 4 were undershot for children’s production speech (CPS) compared with those found in CDS. The pitch range of the SuABT was smaller in CPS, while their duration was longer. The production of falling SuABT exhibited significant developmental changes during the 3–4 age range, stabilized during 4–5 years, and approached the level of CDS after 6 years old. There was also evidence of prosodic entrainment between CDS and CPS.