List intonation in pre-schoolers with normal and disordered language development

The principal aim of this study was to evaluate pre-schoolers' expressive intonation in light of current debates about the underlying nature of language impairment (LI). Children with LI typically have deficits in grammar, a component of language that is phonologically represented on the segmental level. The hypothesis is that children with LI do not have deficits of this type when grammar is conveyed by intonation, a pitch-based component of language that is phonologically represented on the suprasegmental level. This study focused on the richly diversified suprasegmental patterns of sentences in which the speaker produces a series of items in a list. To address the hypothesis, list intonation in the speech of 4-year-olds with and without LI was acoustically analysed. Lists produced by children with LI were comparable to those produced by children with normal language development (NL). The results do not support the claim that LI stems from a poor understanding of grammatical principles. Rather, LI reflects an underlying impairment of segmental information processing. The discussion focuses on two characteristics of pitch contours which may account for the resilience of intonation in children with LI. Namely, steady state versus transient signals and universal symbol meanings versus arbitrary relationships between form and function.