Articulatory inconsistencies in the speech of normal children.

The spontaneous speech of three children about three years old was recorded and transcribed into CnV syllabic units. Cn represents any number of consonants preceding a vowel and is not lexically constrained. Inconsistent production of /s/ and /z/ was found to be related to motor sequencing constraints independent of word boundaries. The results support a model of speech physiology as well as theoretical formulations of child speech production within an adult phonological system.