This includes motor planning and execution, pronunciation, phonological and articulation patterns (as opposed to content and grammar which is language).
[2] Lanky and Williams (2005)[3] suggested that fetuses could respond to pure tone stimuli of 500 Hz as early as 16 weeks.
Rvachew (2007)[5] described three developmental stages in which a child recognizes or discerns adult-like, phonological and articulatory representations of sounds.
In the first stage, the child is generally unaware of phonological contrast and can produce sounds that are acoustically and perceptually similar.
In the second stage the child is aware of phonological contrasts and can produce acoustically different variations imperceptible to adult listeners.
Finally, in the third stage, children become aware of phonological contrasts and produce different sounds that are perceptually and acoustically accurate to an adult production.
Hazan and Barrett (2000)[6] suggest that this development can cotton into late childhood; 6- to 12-year-old children showed increasing mastery of discriminating synthesized differences in place, manner, and voicing of speech sounds without yet achieving adult-like accuracy in their own production.
Knowing when a speech sound should be accurately produced helps parents and professionals determine when child may have an articulation disorder.