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This study was intended to replicate and extend previous findings that (a) during fluent speech persons who stutter (PS) and those who do not (NS) differ in their vocal tract closing movements (L. Max, A. J. Caruso, & V. L. Gracco, 2003) and (b) ratios relating lip and tongue speed to jaw speed increase with stuttering severity (M. D. McClean & C. R. Runyan, 2000). An electromagnetic system was used to record movements of the upper lip, lower lip, tongue, and jaw of 43 NS and 37 PS during productions of a nonsense phrase and a sentence. Measurement and analysis of movement speeds, durations, and ratios of lip and tongue speed to jaw speed were performed on fluent productions of a nonsense phrase and sentence. Statistical comparisons were made between PS with low and high stuttering severity levels (LPS and HPS) and NS. Significant variations across groups in movement speed and duration were observed, but the pattern of these effects was complex and did not replicate the results of the two earlier studies. In the nonsense phrase, significant reductions in lower lip closing duration, jaw closing duration, and jaw closing speed were seen in PS. In the sentence task, HPS showed elevated tongue opening and closing durations. For tongue opening in the sentence, LPS showed elevated speeds and HPS showed reduced speeds. The elevated speeds for LPS are interpreted as a contributing factor to speech disfluency, whereas the reduced speeds and increased durations in HPS are attributed to adaptive behavior intended to facilitate fluent speech. Significant group effects were not seen for the speed ratio measures. Results are discussed in relation to multivariate analyses intended to identify subgroups of PS. KEY WORDS: stuttering, orofacial movements, tongue, jaw, lips, Beginning primarily with the investigations of Zimmermann (1980a), there has been a continuing effort to characterize possible differences in the movements underlying the fluent speech of persons who stutter (PS) [...]

This investigation attempted to clarify the relationship between stuttering in young children and the language factors of length and grammatical complexity. Sentences containing stutterings within the first few words, as produced by 12 stutterers (4-6 years old) in spontaneous conversational dyads, were analyzed for length and grammatical complexity. Results indicated that sentences in which an episode of stuttering occurred within the first three words were significantly longer and more complex than sentences that were free of perceptible stuttering and all other forms of fluency failure. Implications of these findings for the clinician are presented and discussed.