Speech Production Analyses: Characterizing Typical Development versus Childhood Apraxia of Speech

Abstract

Childhood Apraxia of Speech (CAS) is a controversial diagnosis that is frequently based on clinical perceptions, with treatment success based on the same perceptual measures. Because additional, less abstract diagnostic and treatment outcome procedures are needed, a series of quantitative trials were chosen for the current research to potentially assist in the diagnosis and evaluation of treatment for those with CAS. The study included two participants, one child with typically developing (TD) speech and one diagnosed and verified by current protocols as having CAS. Kinematic and acoustic measures were used to calculate spatiotemporal index, speech-pause time, and lexical stress. The spatiotemporal index was factored using kinematic data and computer-based algorithms. Acoustic data were used to evaluate speech versus pause time as well as lexical stress. Speech-pause time was calculated by measuring speech time in comparison with pause times both between and within words. Lexical stress was calculated by computing ratios involving vowel length, mean frequency, and mean amplitude of the first syllable over the second syllable. The participant with CAS displayed greater inconsistency with both the lower and upper lip during repetitions of "Buy Bobby a puppy"; with a higher factored spatiotemporal index for both lips as compared to that of the TD participant. In a story retell task, acoustic analyses of participants' responses revealed increased total utterance time in addition to increased pause time percentage in the participant with CAS versus the TD participant. During repetition of eight trochaic words, the participant with CAS presented greater mean lexical stress while the TD participant displayed stress primarily on the initial syllable. These results provide feasibility for using the given measures to differentiate speech productions of TD children from those with CAS. Additional study of the current measures on a larger scale with TD speech participants as well as in comparison with participants exhibiting other speech sound disorders is recommended.