Acoustic correlates of primary motor speech disorders in children during oral and hand tasks

Abstract

Primary child speech disorders have been subclassified variously. One proposed subtype, childhood apraxia of speech (CAS), results from motor programming deficits in speech production, and associated characteristics include limited phoneme inventory, variability in production, and difficulty with speech prosody, e.g., monostress and monopitch. The purpose of this study was to identify acoustic correlates of oral and limb movements, derived from the hypothesis of a generalized timing deficit, that characterize this disorder subtype differentially from other disorder subtypes. Twelve children (age 4;7 to 6;6), of which eight were labeled with CAS, and 12 age- and gender-matched peers participated in a variety of oral motor and hand tasks. K-means clustering generated three disorder subgroups in the sample of participants with speech disorders, two of which were populated with CAS labels. Distinguishing characteristics included accuracy of vowel duration in a nonword imitation task, accuracy of clap interval duration in a clapped rhythm imitation task, rate of syllable repetition, durations of unstressed but not stressed vowel durations, and breath group duration. Taken together, these results are consistent with the view that deficits in timing accuracy, movement speed, and breath support underlie at least one subtype of idiopathic speech disorder.