Steven Pinker compares a child babbling to a person fiddling with a complex hi-fi system in an attempt to understand what all the controls do. Most babbling consists of a small number of sounds, which suggests the child is preparing the sounds it will need to speak the language it is exposed to.
Infants who are unable to make sounds during this phase show considerable delay in their acquisition of language, but catch up entirely. Infants who are deaf are also delayed in their babbling, and do not attain the same level of complexity. However, if they are exposed to sign language, they babble with their hands at a similar rate of development to hearing babies.
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