Research Paper: Investigation of Acoustic Characteristics of Speech Motor Control in Children Who Stutter and Children Who Do Not Stutter

Stuttering is a developmental disorder of speech fluency with unknown causes. One of the proposed theories in this field is deficits in speech motor control that is associated with damaged control, timing, and coordination of the speech muscles. Fundamental frequency, fundamental frequency range, intensity, intensity range, and voice onset time are the most important acoustic components that are often used for indirect evaluation of physiological functions underlying the mechanisms of speech motor control. The purpose of this investigation was to compare some of the acoustic characteristics of speech motor control in children who stutter and children who do not stutter.
This research is a descriptive-analytic and cross-sectional comparative study. A total of 25 Azari-Persian bilingual boys who stutter (stutters group) and 23 Azari-Persian bilinguals and 21 Persian monolingual boys who do not stutter (non-stutters group) in the age range of 6 to 10 years participated in this study. Children participated in /a/ and /i/ vowels prolongation and carrier phrase repetition tasks for the analysis of some of their acoustic characteristics including fundamental frequency, fundamental frequency range, intensity, intensity range, and voice onset time. The PRAAT software was used for acoustic analysis. SPSS software (version 17), one-way ANOVA, and Kruskal-Wallis test were used for analyzing the data.
The results indicated that there were no significant differences between the stutters and non-stutters groups (P>0.05) with respect to the acoustic features of speech motor control .
No significant group differences were observed in all of the dependent variables reported in this study. Thus, the results of this research do not support the notion of aberrant speech motor control in children who stutter.