The development of articulatory signatures in children

The ability to perceive and produce sounds at multiple time scales is a skill necessary for the acquisition of language. Unlike speech perception, which develops early in life, the production of speech sounds starts at a few months and continues into late childhood with the development of speech-motor skills. Though there is detailed information available on early phonological development, there is very little information on when various articulatory features achieve adult-like maturity. We use modern spectral analysis to investigate the development of three language features associated with three different timescales in vocal utterances from typically developing children between 4 and 8 years. We make comparisons with adult speech and find age dependence in the appearance of these features. Results suggest that as children get older they exhibit increasingly more power in features associated with shorter time scales, thereby indicating the maturation of fine motor control in speech. Such data from typically developing children could provide milestones of speech production at different timescales. Since impairments in spoken language often provide the first warning signs of a language disorder we suggest that speech production could also be used to probe language disorders.