burb

Example:He was so sleepy that he mumbled the directions repeatedly.

Definition:To utter indistinctly and indifferently; to murmur.

Example:The baby would gurgle and laugh when tickled.

Definition:To make a bubbling, gurgling sound, like liquid moving in a pipe or a fish struggling in water.

Example:He hummed a tune while humming along with the radio.

Definition:To produce a dull continuous tone, as with the mouth open but no definite articulation.