He made gruff, unintelligible sounds now and then without seeming aware of it.

I looked up at them when Uncle Jean began to make an unintelligible sound.

A sound at my back, slow and rhythmic, but unintelligible.

His mouth moved and some nearly unintelligible sound came out of it.

She heard loud voices, yet they came to her ears as unintelligible sounds.

He could make only muffled, unintelligible sounds and soon choked on those.

A flurry of unintelligible sound filled the next second or so.

She opened her mouth to speak, but only an unintelligible sound emerged.

Her husband grunted something, a stunned and almost unintelligible sound.