babbling

adjective

Emitting a murmuring sound felt to resemble a laugh: bubbling, burbling, gurgling, laughing, rippling. See laughter, sounds/pleasant sounds/unpleasant sounds/neutral sounds or silence.

The noun has one meaning:

Meaning #1: gibberish resembling the sounds of a baby
  Synonyms: babble, lallation

The adjective babbling has 3 meanings:

Meaning #1: talking idly or incoherently
  Synonyms: blathering, blithering, jabbering, gabbling

Meaning #2: continuous low murmuring sound; as especially of water
  Participle of verb: babble (meaning #3)

Meaning #3: making speech sounds