Phrase-final syllable lengthening and intonation in early child speech.

This research describes the development of phrase-final prosodic patterns in nine English-speaking children. The intonation feature of interest is the fall in the fundamental frequency of the voice that occurs in the final syllables of statements. The corresponding feature of speech timing is phrase-final lengthening. The test opposing theories about the relationship between intonation and syllable timing, these boundary features were compared in a longitudinal study of the children's speech development between the mean ages of 16 and 25 months. The results suggest that young children acquire the skills that control intonation earlier than final syllable timing skills. The findings support the hypothesis tht final lengthening in the speech of 2-year-olds is a learned prosodic feature that cannot be accounted for as a secondary effect of inherent speech production constraints. In addition, a consistent pattern of final lengthening began to emerge when the children were making the transition to combinatorial speech, suggesting a developmental relationship between the child's learning of speech timing and syntax.