Date of Award

6-2015

Degree Name

Master of Arts

Department

Speech, Language and Hearing Sciences

First Advisor

Dr. Stephen M. Tasko

Second Advisor

Dr. Helen M. Sharp

Third Advisor

Dr. James Hillenbrand

Keywords

Stuttering, formant, feedback, fluent, etiology

Access Setting

Masters Thesis-Open Access

Abstract

A recent theory proposed by Civier and colleagues (Civer et al. 2010; Civer et al. 2013) developed a model of stuttering that implicates a faulty feedforward control system. The hypothesis suggests that stuttering results from relying too heavily on sensory feedback to guide speech movements. An overreliance on sensory feedback would result in subtle anomalies in fluent speech (such as slowed articulatory transitions) as well as overt stuttering behaviors (such as sound repetitions). The present study tested this general hypothesis by comparing articulatory transition rates of adults who do and do not stutter across casual and fast speech rates. Participants included 26 adults who stutter (AWS) and 28 normally fluent speakers (NFS) drawn from the Walter Reed-Western Michigan University Stuttering Database. Acoustic measures of articulatory transitions between the initial bilabial plosive /b/ and subsequent vowel /æ/ for the test utterance “a bad daba” (/ə bædæbə/). Acoustic data were analyzed for the following five measures 1) overall speech rate, 2) first and second formant transition durations, 3) first and second formant transition rates. For all measures, AWS tended to produce longer formant transition durations and slower transition rates compared to NFS, but the differences were not significant. The findings suggest that, there are some differences in formant values for AWS compared to NFS which are not significant. In general, findings from the current study do not provide strong support for the overreliance on feedback hypothesis.

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