Children's articulatory limitations shape their grammar: Evidence from a common sound substitution
Some of the speech sound substitutions that children produce have clear analogues in the phonologies of fully-developed languages around the world. However, other child speech patterns have no counterpart in adult phonologies and may not be readily accommodated by existing phonological models. I will present case study evidence from a 4-year-old boy exhibiting one such process, positional velar fronting. It has been argued that positional velar fronting arises when articulatory limitations particular to child speakers are incorporated into the grammar, creating child-specific constraints that will be eliminated in the course of biological maturation (Inkelas & Rose, 2003, 2008). I will demonstrate that the new case study data point to a specific speech-motor limitation as the cause of positional velar fronting. It is known that young children have difficulty executing discrete movements of the tongue, preferring to move the tongue and the jaw together as a single unit (MacNeilage & Davis, 1990). Independent control of the tongue becomes more difficult when gestures are larger and more forceful. Here it will be shown that a grammatical constraint incorporating this articulatory limitation, termed MOVE-AS-UNIT, can account for both positional and segmental factors seen to condition velar fronting in the case study data set.