A wide body of research has examined complexity across the domains of speech and language production (e.g., Gierut, 2001). However, little remains known about complexity within the motoric domain. When a speech impairment impacts motor planning/programming skills, as in childhood apraxia of speech (CAS), a better understanding of motoric complexity is critical to support more effective stimulus design for assessment and treatment. To address this gap, the current work presents a framework of motoric complexity where stimuli differ according to movement elements across a sound sequence (i.e., consonant transitions and vowel direction). This framework was then examined in children with CAS, other speech sound disorders (SSD), and typical development (TD).
Twenty-four children (CAS = 8; SSD = 8; TD = 8), 5–6 years of age, participated in this study. The children were asked to produce words that varied in motoric complexity while transcription, acoustic, and kinematic data were collected using a digital recorder and a facial motion capture system. Multidimensional analyses were conducted to examine speech production accuracy, speech motor variability, and temporal control. Findings revealed poorer accuracy, longer movement duration, and greater speech motor variability in children with CAS than TD (across all measures) and other SSDs (accuracy and variability). However, group membership did not mediate performance on this task and all children demonstrated differences in speech performance across levels of the motoric complexity framework. Findings may therefore reflect a developmental sequence of speech motor control, though it is questionable whether performance can be interpreted in a similar manner across groups of children.
Results of this study are believed to reveal gradations of motoric complexity within the presented framework. Speech motor variability and duration incrementally increased as movement demands became more challenging across vowel directions, most notably in the context of varied consonant combinations that more closely approximated natural speech. Sound sequences that required minimal adjustments of articulatory gestures also posed a unique challenge to all children. Overall, these findings support a framework of motoric complexity, in addition to the importance of considering motoric properties of sound sequences when evaluating speech production skills and designing experimental and treatment stimuli.
|Advisor:||Grigos, Maria I.|
|Commitee:||Buchwald, Adam, Levi, Susannah V., Magill, Richard, McAllister, Tara|
|School:||New York University|
|Department:||Communicative Sciences and Disorders|
|School Location:||United States -- New York|
|Source:||DAI-B 80/11(E), Dissertation Abstracts International|
|Keywords:||Childhood apraxia of speech, Motor complexity, Motor learning, Motor speech disorders, Speech motor control, Speech sound disorders|
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