Investigating Potential Mechanisms Underlying Stuttering Reduction

Research output: ThesisDoctoral Thesis

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Abstract

Stuttering is a complex communication disorder. Limited understanding of
exactly how and by what means stuttering reduces presents a key challenge to
increasing treatment efficacy. Such knowledge will enable treatments to directly target mechanisms underlying stuttering reduction, thereby increasing their efficacy and/or efficiency. This research sought to discover more about how stuttering reduces following prolonged speech (PS) and syllable-timed speech (STS) treatment and with altered auditory feedback (AAF). It did so by investigating pre to posttreatment differences in a range of variables highlighted for their potential role as mechanisms underlying stuttering reduction.

Explanations of stuttering reduction with PS and prior studies into how
stuttering reduces with PS were reviewed. Phonation intervals (PIs), vowel duration (VD), speaking fundamental frequency (Sf0) and articulation rate (AR) were selected for investigation following PS treatment. Study 1 investigated posttreatment differences in these variables from the spontaneous speech of seven adult participants of an intensive PS treatment program. Individual patterns of posttreatment difference in variables were observed, yet reduction in the variability of components of syllabic stress (VD and/or Sf0) arose as one potential mechanism underlying stuttering reduction with PS.

Next, explanations of stuttering reduction with STS and prior studies into how
stuttering reduces with STS were reviewed. VD, Sf0 and AR were selected for
investigation following STS treatment. Linguistic variables of mean length of utterance, percentage of complex sentences, number of different words, number of total words, and proportion of assertive conversational speech acts were also selected because of growing interest in STS treatment with young children during the period of language development. Study 2 investigated posttreatment differences in these variables from the spontaneous speech of four school aged children following an STS treatment. Again, individual patterns of posttreatment difference in variables were observed, and reduction in the variability of components of syllabic stress (VD and/or Sf0) also arose as a pattern across individual participants, supporting the possibility that this might be
one potential mechanism underlying stuttering reduction with STS. Study 3 investigated posttreatment differences in these same variables from the spontaneous speech of six preschool aged children following a similar STS treatment. Individual patterns of posttreatment difference in variables were observed, and these did not clearly support any particular variables as potential mechanisms underlying stuttering reduction with STS.

Explanations of stuttering reduction with AAF and prior studies into how
stuttering reduces with AAF were also reviewed. VD, Sf0 and AR were selected for investigation with AAF. Study 4 investigated differences in these variables from the spontaneous speech of three adult participants during multiple AAF conditions. Individual patterns of difference during AAF conditions were observed, and these did not clearly support any particular variables as potential mechanisms underlying stuttering reduction with AAF.

Collectively, these research findings make a valuable contribution to the limited
understanding of how stuttering reduces following PS and STS treatment and with AAF. Findings especially promote interest in learning more about the potential role of reduction in variability of components of syllabic stress (VD and/or Sf0) in stuttering reduction. With an ultimate view towards improving treatment efficacy and efficiency, they direct treatment development towards continued adaptation of and experimentation with PS and STS treatments.
Original languageEnglish
QualificationDoctor of Philosophy
Awarding Institution
  • Charles Sturt University
Supervisors/Advisors
  • Halaki, Mark, Co-Supervisor
  • Packman, Ann, Co-Supervisor, External person
  • Wilson, Linda, Co-Supervisor
Award date01 Nov 2015
Place of PublicationAustralia
Publisher
Publication statusPublished - 2015

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