Segmental/lexical influences on tone accuracy in Mandarin-speaking children
Emergence of accuracy is a first step toward acquiring adult-like phonological abilities. Mandarin Chinese is a tone language where speakers employ both tonal and segmental properties to code lexical meanings. Study of this dual-level complexity of tone and segment enables a broader view of how phonology is acquired than the view afforded by study of Indo-European languages. Understanding the interaction between phonatory properties for tone and articulatory adjustments for segments in emergence of early words helps to understand more generally the first steps toward the complex system embodied in phonology. The present study investigated tone acquisition in relation to segmental and lexical development in Mandarin-speaking children in the earliest word stages. Spontaneous speech samples were collected longitudinally from 12 to 24 months from four Mandarin-speaking children. The relationships between tone accuracy, segmental accuracy, and word-level variables were examined quantitatively over time. Results indicated that tone accuracy is not always higher than segmental accuracy. The relationship between these two seems to be influenced by the physiological complexity of tonal shapes and children’s developmental age. Autonomy of control over phonatory adjustments for tone and articulatory adjustments for segments was already apparent. Children were not sensitive to the contrastivity (characterized by Productive Tone Neighborhood Density) involved in tonal categories with a vocabulary of less than 50 words. Associations between production accuracy and word-level variables (articulatory complexity, neighborhood density and word frequency) established based on later developmental periods were not found in younger Mandarin-speaking children. Findings suggest that tonal acquisition at the onset of speech development is not a passive process where innate phonological knowledge is revealed solely through children’s maturation. Rather, phonological knowledge is established on the basis of children’s pre-linguistic motor capacities in concert with cognitive learning occurring via the expansion of their lexicon. Tones and segments may be produced as holistic entities in early words. Tone acquisition at the onset of word learning is more child-centered in that availability of tonal forms to the child’s production system underlies accuracy. Influences from lexical properties of word would only be apparent when phonological knowledge of tonal categories is established with vocabulary expansion.