Why is babbling so important? The infant is like a person who has been given a complicated piece of audio equipment bristling with unlabled knobs and switches but missing the instruction manual. In such situations people resort to what hackers call frobbing - fiddling aimlessly with the controls to see what happens. The infant has been given a set of neural commands that can move the articulators every which way, with wildly varying effects on the sounds. By listening to their own babbling, babies in effect write their own instruction manual; they learn how much to move which muscle in which way to make which change in the sound. This is a prerequisite to duplicating the speech of their parents. Some computer scientiests, inspired by the infant, believe that a good robot should learn an internal software model of its articulators by observing the consequences of its own babbling and flailing.
Steven Pinker
The Language Instinct, p266