The Acquisition Of Tone In Mandarin-speaking Children

The purpose of the present study is to investigate the acquisition of tone in early language development by using longitudinal data of two Mandarin-speaking children living in Changsha. The observation began when the children were one year old and ended when they were two years three months at a monthly interval. The recognizable words/utterances in the 18-hour speech data of each child were transcribed into IPA and five-point-scale tone letters both by perception and by acoustic methods. The tonal acquisition process was analyzed from phonetic aspects and phonological aspects.Within the traditional framework used for the investigation of tonal acquisition and by adopting a 70% accuracy rate as the criteria determining tone acquisition, we found that Tone 1 (level) is acquired first, followed by Tone 4 (falling) and Tone 2 (rising), and Tone 3 (fall-rise) is the last to be acquired. Unlike previous findings showing the early mastery of tone at two years old or even before, ours shows that children did not acquire most of the tone categories around two years three months. However, if lexicon factor is integrated into the criteria for tone acquisition, all tone categories are considered as acquired around the age of two. But this does not entail children's ability to pronounce all lexicon items in the same tone category accurately. Therefore, we claim that the divergence of previous studies on the issue of the early mastery of tone may stem from neglecting lexicon factors in the determination criteria for tone acquisition. Furthermore, tone substitution pattern of the children in the present study differs from that in previous studies. Children prefer to use falling contours rather than rising contours to replace Mandarin Tone 3. Target Tone 1 tends to be replaced by both rising and falling contours with comparable frequency. Whether such differences can be attributed to the dialectal influence require further research.Our data reveal that lexicon plays a primary role in children's early tonal acquisition. Tonal acquisition in children's early speech is far from being an across-the-board phonological process but diffuses through the lexicon. The lexicon-dependent fashion in tonal acquisition is evidenced from the difference in tonal production accuracy, substitution patterns and tonal developmental path of lexical items in the same tone category. This supports Ferguson & Farwell (1975) by regarding lexical item as the basic unit in early phonological acquisition from a suprasegmental perspective.We also find that the distribution pattern of tonal contours, selection of target lexical items and tone substitution patterns in the two subjects'early speech reflect pitch characteristics exhibited in their babbling period, therefore lending support to the continuity hypothesis on phonological development.