Sotto Voce
Wikipedia
Sotto voce (/ˈsɒtoʊ ˈvoʊtʃeɪ/; Italian: [ˈsotto ˈvoːtʃe], literally “under voice”) means intentionally lowering the volume of one’s voice for emphasis. The speaker gives the impression of uttering involuntarily a truth which may surprise, shock, or offend. Galileo Galilei’s (probably apocryphal) utterance “Eppur si muove” (“Nonetheless, [the Earth] does move”), spoken after recanting his heliocentric theory, is an example of sotto voce utterance.
Mirriam-Webster Dictionary
under the breath : in an undertone; also : in a private manner – very softly —used as a direction in music
Cambridge Dictionary
