Characteristics of Diadochokinesis in Typically Developing Children and Adults

Purpose: The purpose of this study was to examine the characteristics of the rate and perceptual judgment of diadochokinesis (DDK) in typically developing children and adults. Methods: Participants were typically developing children aged 2;6 to 9;11 and normal adults. For DDK tasks, they were asked to repeat [p*a], [t*a], [k*a], [p*at*a], and [p*at*ak*a] accurately and quickly with one breath. The number of repetitions per second was measured as DDK rate for each stimuli. The perceptual judgment of DDK were also performed in terms of regularity, rate, and accuracy using a three-point scale. Results: Children showed increases in the number of repetitions per second for all the DDK tasks with age. However, all the children groups between ages 2;6 and 9:11 exhibited significantly slower DDK rates than adults. In the perceptual judgment of DDK tasks, accuracy, rate, and consistency of sequential motion rates using [p*at*a] and [p*at*ak*a] showed statistically significant differences across age groups. Children demonstrated similar accuracy of SMR tasks with adults after age 6;0. Conclusion: This study showed developmental patterns of speech motor skills based on rate, accuracy, and consistency of DDK tasks. This study provides references for assessing speech motor skills related to children with speech difficulties.