Determination and comparison of reaction time of phonation in stutterers and non-stutterers in two group of age 10-20, 20-30

Some researcher suggest that stuttering is a temporal disruption of the simultaneous and successive programming of muscular movements required to produce a speech sound and they say speech motor in stutterers associated with reduced timing variable rather than non stutterers such as reaction time. Reaction time is a standard criterion that can show nature of differences of phonation between stutterers and non-stutterers. The aim of this study is determination and comparison of reaction time of phonation in stutterers and non-stutterers. this was descriptive- analytic study and selected 22 stutterers and 22 no stutterers from 10-30 years old and request them when heard stimulation as quickly as possible in response then recorded both of stimulation and answers by Praat software and measured interval between them. result of this study show mean of reaction time in stutterers is more than no stutterers and this difference is more significant in 20-30 years old. But differences in two group of age do not significant. to consider، there is problem in voice onset in stutterers so this problem can be result from slower VRT could result problem such as struggle، avoiding and anticipatory behaviors، disorder in neuro-motor factors، timing force that stutterers feel in this task that this problem specially in adult stutteres are more than children because they have more experience in stuttering.