in an undertone (literally 'under the voice')

Sotto voce translates roughly to "under one's breath." You can think of it like muttering or whispering.

Sotto voce is Italian. That means to 'speak under one's breath', as if one was talking to himself.

The term "sotto voce" can be translated as "in soft tones" or "in an undertone". An example would be to lower the voice in order to emphasis the spoken words.

"Sotto voce" is an Italian term that translates to "in a quiet voice" or "in a soft voice" in English. It is often used to describe speaking in a hushed or confidential manner.