Temporal characteristics of "functionally" misarticulated /s/ in 4- to 6-year-old children.

This paper reviews instrumental studies of "functional" misarticulations in children and reports an experiment involving acoustic measures of the duration of normally articulated and misarticulated /s/. Three subject groups (n = 7 in each group) included normally articulating adults, normally articulating children, and children who misarticulate the /s/ sound. Multiple repetitions of nonsense sequences containing /s/ were obtained from each subject, and group and individual subject comparisons were based on means, standard deviations, and the derived coefficient of variation associated with /s/ duration. Results indicate that /s/ durations of misarticulating children are significantly more variable than those of normally articulating children, and that this difference is more striking in /s/-stop clusters than in the case of singleton /s/. The possibility is raised that the variability differences between the two child groups may reflect differences in speech motor control capabilities. It is suggested that such control differences should predict temporal variability differences between the two child groups for sounds which are articulated correctly by children in both groups. In addition, these variability differences should be observed for the spectral dimension of speech sound production, since this measure is sensitive to control of articulatory configuration.