Effects of age and vocabulary size on production accuracy and acoustic differentiation of young children's sibilant fricatives

This paper reports preliminary results of a study of the development of sibilant fricatives /s/ and /ʃ/ in young children. Results show that transcribed accuracy increased over the age range studied (28 to 39 months) and that children with larger vocabularies produced fricatives more accurately than ones with smaller vocabularies. Spectral characteristics were measured for productions transcribed to be sibilant. The separation between the spectra of target /s/ and target /ʃ/ also increased over the age range, and was greater in children with larger-sized vocabularies.