Prosodic variability in the speech of children who stutter

Abstract

Developmental stuttering is a heterogeneous language disorder characterized by persistent speech disruptions, which are generally realized as repetitions, blocks, or prolongations of sounds and syllables (DSM-IV-R, 1994). While previous studies have uncovered ample evidence of deficits in both “higher-level” linguistic planning and “lower-level” motor plan assembly, identifying the relative contribution of the specific factors underlying these deficits has proved difficult. Phrasal prosody represents a point of intersection between linguistic and motoric planning, and therefore a promising direction for stuttering research. In the present study, 12 children who stutter (CWS) and 12 age-matched controls (CWNS) produced sentences varying in length and syntactic complexity. Quantitative measures (F0, duration, and intensity) were calculated for each word, juncture, and utterance. Overall, CWS produced a narrower F0 range across utterance types than did CWNS, while utterance duration did not differ significantly between groups. Within utterances, CWS (but not CWNS) produced a greater degree of pre-boundary lengthening preceding relative clauses in syntactically complex sentences, as well as higher F0 variability at these juncture points. Such differences suggest that for CWS utterance planning is sensitive to syntactic complexity, possibly reflecting either a deficit in syntactic processing or the relative effects of syntactic processing on a strained processing system.