I heard muttering, then realized that there were two of them.

She had put the cover over it, but the bird could be heard muttering to himself inside.

Apparently the man is reading, since he can be heard muttering and turning the pages of a book.

She strained her ears and heard muttering from the other room.

Ned heard muttering from beneath the windows and the far end of the hall.

Afterward, he was heard muttering something about being an "invisible man."

Barbara can be heard muttering from across the room.

Scott and an engine technician could be heard muttering in the background.

During the bridge of the song, Vedder can be heard muttering.

She heard muttering above her, but feared to listen, lest it was death being summoned.