As young children are getting ready to talk, they begin to coo and Even children who are deaf do this for a periods of time.

As young children are getting ready to talk, they begin to coo and babble.

Explanation:

There are many milestones a baby should reach during its development, including language milestones. Cooing is the baby's first sound production besides crying, and babbling is the next stage, which includes the repetition of syllables (e.g. bababa) without any meaning. This will eventually turn into the so-called baby jargon (also called nonsense speech), and the next stage will be the baby's first word.