Compensatory Strategies in the Developmental Patterns of English /s/: Gender and Vowel Context Effects

The developmental trajectory of English /s/ was investigated to determine the extent to which children's speech productions are acoustically fine-grained. Given the hypothesis that young children have adultlike phonetic knowledge of /s/, the following were examined: (a) whether this knowledge manifests itself in acoustic spectra that match the gender-specific patterns of adults, (b) whether vowel context affects the spectra of /s/ in adults and children similarly, and (c) whether children adopt compensatory production strategies to match adult acoustic targets.

Several acoustic variables were measured from word-initial /s/ (and /t/) and the following vowel in the productions of children aged 2 to 5 years and adult controls using 2 sets of corpora from the Paidologos database.

Gender-specific patterns in the spectral distribution of /s/ were found. Acoustically, more canonical /s/ was produced before vowels with higher F1 (i.e., lower vowels) in children, a context where lingual articulation is challenging. Measures of breathiness and vowel intrinsic F0 provide evidence that children use a compensatory aerodynamic mechanism to achieve their acoustic targets in articulatorily challenging contexts.

Together, these results provide evidence that children's phonetic knowledge is acoustically detailed and gender specified and that speech production goals are acoustically oriented at early stages of speech development.