sotto voce

Though he’s given to explosive bursts of speech, as the character has developed, the humor he plays becomes more subtle and quiet, peppered with muttered comments and sotto voce asides he means to be heard.

But instead, the trip is taking place sotto voce.

Heads bent close in the candlelight, speaking sotto voce, they made an almost rom-com pair.

But his subsequent sotto voce remark, to the effect that he probably wouldn’t give any of the Manhattan Project scientists clearance under those rules, doesn’t appear anywhere in the 1,011-page hearing transcript.

Seated next to him at a public hearing, you were in constant danger of laughing out loud at his sotto voce commentaries.