Individual Variability in Delayed Auditory Feedback Effects on Speech Fluency and Rate in Normally Fluent Adults Purpose Delayed auditory feedback (DAF) is known to induce stuttering-like disfluencies (SLDs) and cause speech rate reductions in normally fluent adults, but the reason for speech disruptions is not fully known, and individual variation has not been well characterized. Studying individual variation in susceptibility to DAF may identify factors that ... Research Article
Research Article  |   April 01, 2013
Individual Variability in Delayed Auditory Feedback Effects on Speech Fluency and Rate in Normally Fluent Adults
 
Author Affiliations & Notes
  • HeeCheong Chon
    Chosun University, Gwangju, Korea
  • Shelly Jo Kraft
    Wayne State University, Detroit, MI
  • Jingfei Zhang
    University of Illinois, Champaign
  • Torrey Loucks
    University of Illinois, Champaign
  • Nicoline G. Ambrose
    University of Illinois, Champaign
  • Correspondence to HeeCheong Chon: hchon@chosun.ac.kr
  • Editor: Anne Smith
    Editor: Anne Smith×
  • Associate Editor: Melanie Matthies
    Associate Editor: Melanie Matthies×
Article Information
Speech, Voice & Prosodic Disorders / Fluency Disorders / Speech, Voice & Prosody / Speech / Research Articles
Research Article   |   April 01, 2013
Individual Variability in Delayed Auditory Feedback Effects on Speech Fluency and Rate in Normally Fluent Adults
Journal of Speech, Language, and Hearing Research, April 2013, Vol. 56, 489-504. doi:10.1044/1092-4388(2012/11-0303)
History: Received November 7, 2011 , Revised April 30, 2012 , Accepted August 15, 2012
 
Journal of Speech, Language, and Hearing Research, April 2013, Vol. 56, 489-504. doi:10.1044/1092-4388(2012/11-0303)
History: Received November 7, 2011; Revised April 30, 2012; Accepted August 15, 2012
Web of Science® Times Cited: 5

Purpose Delayed auditory feedback (DAF) is known to induce stuttering-like disfluencies (SLDs) and cause speech rate reductions in normally fluent adults, but the reason for speech disruptions is not fully known, and individual variation has not been well characterized. Studying individual variation in susceptibility to DAF may identify factors that predispose an individual to be more or less dependent on auditory feedback.

Method Participants were 62 normally fluent adults. Each participant performed a spontaneous speech task in 250-ms DAF and amplified nondelayed auditory feedback (NAF) conditions. SLDs, other disfluencies (ODs), speech errors (SEs), and articulation rate (AR) were measured under each condition.

Results In the DAF condition, SLDs and SEs significantly increased, and AR decreased. Sex had a limited effect in that men exhibited higher rates of ODs and faster AR than women. More important, parametric cluster analysis identified that 2- and 3-subgroup solutions reveal important variation that differentiates tendencies toward disfluency changes and rate reduction under DAF, which are theoretically and empirically preferred to a single-group solution.

Conclusion Individual variability in response to DAF may be accounted for by subgroups of individuals. This suggests that certain normally fluent individuals could be more dependent on intact feedback to maintain fluency.

Acknowledgments
This research was supported by National Institute on Deafness and Other Communication Disorders Grant R01-DC05210 (Ehud Yairi, original principal investigator [PI]; Nicoline Ambrose, second PI). It was also supported by a University of Illinois Research Board grant (Torrey Loucks, PI). This study was part of the first author's doctoral dissertation, which was conducted within the Illinois International Stuttering Research Program at the University of Illinois at Urbana-Champaign and was codirected by Torrey Loucks (fourth author) and Nicoline Ambrose (fifth author). The second author (Shelly Jo Kraft) was a doctoral student at the University of Illinois when this research was conducted. We greatly appreciate Ehud Yairi's encouragement and editorial contributions to this article.
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