The Effect of Sample Size on the Assessment of Stuttering Severity The relationships between the length of the speech sample and the resulting disfluency data in 20 stuttering children who exhibited a wide range of disfluency levels were investigated. Specifically, the study examined whether the relative number of stuttering-like disfluencies (SLD) per 100 syllables, as well as the length of disfluencies ... Research Article
Research Article  |   February 01, 2006
The Effect of Sample Size on the Assessment of Stuttering Severity
 
Author Affiliations & Notes
  • Jean Sawyer
    The University of Illinois at Urbana-Champaign
  • Ehud Yairi
    The University of Illinois at Urbana-Champaign
  • Contact author: Jean Sawyer, Department of Speech Pathology and Audiology, 204 Fairchild Hall, Illinois State University, Normal, IL 61790. Email: jsawyer@ilstu.edu
Article Information
Speech, Voice & Prosodic Disorders / Fluency Disorders / Speech, Voice & Prosody / Research Articles
Research Article   |   February 01, 2006
The Effect of Sample Size on the Assessment of Stuttering Severity
American Journal of Speech-Language Pathology, February 2006, Vol. 15, 36-44. doi:10.1044/1058-0360(2006/005)
History: Received October 25, 2004 , Revised May 24, 2005 , Accepted October 13, 2005
 
American Journal of Speech-Language Pathology, February 2006, Vol. 15, 36-44. doi:10.1044/1058-0360(2006/005)
History: Received October 25, 2004; Revised May 24, 2005; Accepted October 13, 2005
Web of Science® Times Cited: 17

The relationships between the length of the speech sample and the resulting disfluency data in 20 stuttering children who exhibited a wide range of disfluency levels were investigated. Specifically, the study examined whether the relative number of stuttering-like disfluencies (SLD) per 100 syllables, as well as the length of disfluencies (number of iterations per disfluent event), varied systematically across 4 consecutive, 300-syllable sections in the same speech sample. The difference in the number of SLD per 100 syllables between the early and later sections of the speech sample was statistically significant. In addition, the length of the speech sample had a critical influence on the identification of stuttering in children exhibiting relatively low levels of disfluency. Also, when a 20% difference in the number of SLD per 100 syllables was taken as a criterion, 50% of the children exhibited upward shifts in continuous speech samples that were longer than 300 syllables (i.e., 600, 900, and 1,200 syllables). Results indicated that, in general, group means for SLD grew larger as the sample size increased. The length of disfluent events did not significantly differ as the sample size increased; however, there were large differences for some children. Implications for clinicians and investigators are discussed.

Acknowledgment
This research was supported by Research Grant R01-DC 05210 from the National Institute on Deafness and Other Communication Disorders, National Institutes of Health, to the second author.
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