The acoustical analysis of children's use of prosody in assertive and directive contexts

Prosodic features of children's utterances were compared across asser tive directive tasks, in order to determine how these acoustical proper ties of speech are used for communication. Methodological difficulties inherent in many previous investigations were averted by using a procedure that ensured that prosody was judged independently of communicative purpose. Four children aged 1;11 were audiotaped while in contexts designed to elicit assertive or directive utterances to an adult. The children's utterances were analysed for intensity and duration as well as beginning, end, peak, and low frequencies, fre quency range, and contour changes. Results showed that in the direc tive context intensity was increased overall. Increased end point fre quency and a trend for increased overall peak frequency were also noted, although the way in which the latter features were used varied with individual children. Beginning frequency and frequency range also showed significant task by child interactions, but no main effect for task. These findings indicate that children at this age use prosodic elements of speech differentially across communicative contexts and code their intentions with multiple features. Differences between chil dren may reflect individual differences or developmental effects.