Mandarin-speaking 6-year-olds can use preboundary pitch range expansion to disambiguate compounds from lists

Pitch can be used for marking boundaries and chunking utterances into different units, e.g., compounds (N₁+N₂, e.g., jellybeans) and their corresponding list forms (N₁, N₂, e.g., jelly, beans). Unlike English, where 5-6-year-olds can use different pitch patterns to mark boundaries in an adult-like manner, Mandarin is a tonal language using pitch for both word meanings (lexical tone) and utterance meanings (e.g., preboundary pitch range expansion). While lexical tones are early acquired, it was unclear when Mandarin-speaking children can use pitch cues to disambiguate compounds and lists. A total of 41 adults and 29 6-year-olds participated in an elicited production task. The pitch range of N1 was measured (highest minus lowest pitch (f0)). Our results showed that similar to adults, 6-year-olds produced a larger pitch range over N₁ in lists compared to compounds for rising and falling tones. However, no pitch range expansion was found for the high-level tone in children or adults. These patterns suggested that 6-year-olds are adult-like in producing preboundary pitch cues that disambiguate compounds and lists. These findings are discussed in terms of the modulation of pitch information at the word and phrase levels and the role of pitch as a cue in response to boundaries in Mandarin.