Speech motor control hypothesis in bilingual children who stutter and children who do not stutter

Objective and Background: Stutteringisa developmentaldisorder ofspeech fluency that the exact causesofithasnot been determined. One of theexpressed theories isdeficit inmotor control ofspeech that damaged control, timingand coordination ofthe muscles. Fudamental frequency, fudamental frequency range, intensity, intensity range and voice onset time are the most importantacoustic components that oftenareused forindirectevaluationphysiological functions underlyingmechanisms of speech motor control. The purpose of this investigation was to compare some ofacoustic characteristicsof speech motor control in Azari-Persian bilingual children who stutter and monolingualand bilingual children who do not stutter.Material and Methods: Thisresearchwas conducted for descriptive-analytic and cross-sectionalcomparativestudy. 25 bilinguals boy stutters and 23 bilinguals and 21 monolinguals boy non-stutters aged in 6 to 10 participated in this study. Children participated in /a/ and /i/ vowels prolongation and carrier phrase repetition tasks to analysis of some acoustic characteristics include fudamental frequency, fudamental frequency range, intensity, intensity range and voice onset time. PRAAT software were used for acoustic analysis. SPSS software andOne-way ANOVA and Kruskal Wallis tests were used for analyzing the data.Findings: Result indicate thatmajor of theacoustic features of motor control ofspeech such asfudamental frequency, fudamental frequency range, intensity, intensity range and voice onset timedid not significant differencesbetween the stutter groupsandnon-stutters(P> .05).Conclusion: Nosignificant group differencesobserved in all of variables reported in this study did not support the notion of aberrant speech motor control in stutters children.

Keywords:

speech motor control , stuttering , acoustic features , fudamental frequency , voice onset time