The Effect of Practice on Variability in Childhood Apraxia of Speech: A Multidimensional Analysis.

Purpose Variability has been interpreted in differing ways according to context (e.g., development, speech impairment, and learning). A challenge arises when interpreting variability in the context of learning for children with speech impairment characterized by high movement variability, as in childhood apraxia of speech (CAS). The objective of this study is to investigate changes in variability in CAS with practice in comparison to patterns seen in children with non-CAS speech sound disorders (SSD) and typical development. Method Speech production variability was examined in 24 children (5-6 years of age) with CAS, non-CAS SSD, and typical development in production of nonwords of varied motoric complexity. Multidimensional analyses were performed using measures of token-to-token speech consistency (percent word consistency), acoustic variability (acoustic spatiotemporal index), and movement variability (lip aperture spatiotemporal index). Changes in variability were examined in each group of children by comparing the first half to the last half of nonword tokens in the same data collection session. The impact of token complexity on practice effects was also explored across groups of children. Results All children displayed increased speech consistency within this practice period (