Not only the usual crackles but voices muttering away in the background.

The first person we saw was Moody Spurgeon sitting on the steps and muttering away to himself.

Silk's expression grew surly, and he wandered away muttering to himself.

The sculptor is muttering away to himself about the broken tail.

The old woman shouldered her bag again, giving him a baleful look, and went muttering away.

I slipped it to him and he staggered away muttering with relief.

He came close to the grave and saw a guy muttering away beside it.

Private Grenoble muttered from his firing hole a few feet away.

I smirked at him again, and he stumped away muttering to himself.

He went away muttering and I took a great slug of the beer.