An acoustic analysis of frontal misarticulation of /s/ in children

In an attempt to investigate the acquisition of fine phonetic control and the nature of phonological representations in children who exhibit speech sound production errors, this study explored temporal, amplitude, and spectral characteristics of frontally misarticulated /s/ and compared these parameters to those associated with correctly articulated /θ/. The subjects included two groups of misarticulating children, aged 5–6 years and 7–8 years and two groups of age-matched normal control subjects. Recordings of /s/ and / θ/ as produced by these subjects in a variety of vocalic contexts were analyzed acoustically; mean duration, amplitude, and centroid frequency measures for the frication noise, and measures of variability were computed and contrasted across the four groups. Results indicated that all groups distinguished /s/ and / θ/ to some extent on all parameters measured. However, centroid values for misarticulated /s/ were lower in frequency than were those for normally-articulated /s/. Results are discussed in relation to the nature of phonological targets in misarticulating children and to the acoustic characteristics of misarticulated /s/ in developing speech production.