Abstract

Previous studies of pre- and post-therapy fluent speech of individuals who stutter have reported longer durations of voiced speech segments and shorter durations of silent intervals, unvoiced speech segments/subsegments. These post-therapy changes in temporal acoustic durations may be associated with by-products of such target behaviors as prolonged syllables and reduced articulatory rate rather than with the speech motor control processes underlying fluency enhancement. The current study aims to uncover acoustic events of post-therapy fluent speech which are related to speech production behaviors underlying fluency enhancement. For this purpose, rather than using prolonged speech, slow initiation of voicing, or a reduced speech rate to facilitate fluency, the children who stutter in the current study received "Normal Talking Process" therapy (Williams, 1979), which teaches both purposeful change of individual speech parameters to increase fluency and behavioral awareness of fluent (easy) versus stuttered(hard)speech. Further, in order to improve interpretations of such an analysis, pre- and post-therapy fluent speech obtained from stuttering children who stutter was compared to similar speech samples produced by normal children.

This study compared absolute durations of temporal acoustic parameters at the subsegmental level of fluent speech produced by stuttering children (N=4) before and after "Normal Talking Process" therapy. These measures were then compared to an age and gender-matched control group of normally fluent children. The findings indicated that voice onset time (VOT) and CV (consonant-vowel) transition duration decreased significantly after therapy. Children who stutter produced significantly longer vowel durations than the control group both before and after therapy. The results was discussed in terms of differential aspects of this treatment.

A number of acoustic studies have compared the pre- and post-therapy fluent speech of both children and adults who stutter. The primary motivation for such investigations is to ascertain whether decreases in stuttering as a result of intervention are associated with alterations in various temporal speech events as represented within the acoustic waveform. According to Metz, Samar, & Sacco (1983), observed changes in the acoustic properties of fluent speech following stuttering therapy may be important indices of "...changes in the operation of motor control process that underlie fluency enhancement, whereas others may be systematic by-products of the particular fluency-enhancing condition. (p. 531)"

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