The Effects of Syntactic Complexity and Sentence Length on the Speech Motor Control of School-Age Children Who Stutter Purpose Early childhood stuttering is associated with atypical speech motor development. Compared with children who do not stutter (CWNS), the speech motor systems of school-age children who stutter (CWS) may also be particularly susceptible to breakdown under increased processing demands. The effects of increased syntactic complexity and sentence length on ... Research Article
Research Article  |   September 19, 2018
The Effects of Syntactic Complexity and Sentence Length on the Speech Motor Control of School-Age Children Who Stutter
 
Author Affiliations & Notes
  • Evan R. Usler
    Department of Speech, Language, and Hearing Sciences, Boston University, MA
    Speech and Feeding Disorders Laboratory, MGH Institute of Health Professions, Boston, MA
  • Bridget Walsh
    Department of Communicative Sciences and Disorders, Michigan State University, East Lansing
  • Disclosure: The authors have declared that no competing interests existed at the time of publication.
    Disclosure: The authors have declared that no competing interests existed at the time of publication. ×
  • Correspondence to Evan Usler: eusler@bu.edu
  • Editor-in-Chief: Julie Liss
    Editor-in-Chief: Julie Liss×
Article Information
Speech, Voice & Prosodic Disorders / Fluency Disorders / Speech, Voice & Prosody / Speech / Research Articles
Research Article   |   September 19, 2018
The Effects of Syntactic Complexity and Sentence Length on the Speech Motor Control of School-Age Children Who Stutter
Journal of Speech, Language, and Hearing Research, September 2018, Vol. 61, 2157-2167. doi:10.1044/2018_JSLHR-S-17-0435
History: Received November 20, 2017 , Revised March 6, 2018 , Accepted April 30, 2018
 
Journal of Speech, Language, and Hearing Research, September 2018, Vol. 61, 2157-2167. doi:10.1044/2018_JSLHR-S-17-0435
History: Received November 20, 2017; Revised March 6, 2018; Accepted April 30, 2018

Purpose Early childhood stuttering is associated with atypical speech motor development. Compared with children who do not stutter (CWNS), the speech motor systems of school-age children who stutter (CWS) may also be particularly susceptible to breakdown under increased processing demands. The effects of increased syntactic complexity and sentence length on articulatory coordination were investigated.

Method Kinematic, temporal, and behavioral indices of articulatory coordination were quantified for school-age CWS (n = 19) and CWNS (n = 18). Participants produced 4 sentences varying in syntactic complexity (simple declarative/complex declarative with a relative clause) and sentence length (short/long). Lip aperture variability (LAVar) served as a kinematic measure of interarticulatory consistency over repeated productions. Articulation rate (syllables per second) was also calculated as a related temporal measure. Finally, we computed accuracy and stuttering frequency percentages for each sentence to assess task performance.

Results Increased sentence length, but not syntactic complexity, increased LAVar in both groups. This effect was disproportionately greater for CWS compared with CWNS. No group differences were observed for articulation rate. CWS were also less accurate in their sentence productions than fluent peers and exhibited more instances of stuttering when processing demands associated with length and syntactic complexity increases.

Conclusions The speech motor systems of school-age CWS appear to be particularly vulnerable to processing demands associated with increased sentence length, as evidenced by increased LAVar. Increasing the length and complexity of the sentence stimuli also resulted in reduced production accuracy and increased stuttering frequency. We discuss these findings within a motor control framework of speech production.

Acknowledgments
This work was supported by a grant awarded to Bridget Walsh (R03 DC013402) from the National Institute on Deafness and Other Communication Disorders. The first author was also funded by grants from the National Institute on Deafness and Other Communication Disorders (R01 DC00559 and T32 DC013017). Special thanks to Anna Bostian for her help in collecting data, Janna Berlin for her help with data analysis, and Barbara Brown for her assistance in recruiting subjects and clinical testing at Purdue University.
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