quietly

being self-assured without being boastful or loud

showing resolve in a calm and understated way

showing satisfaction in a subtle, non-obvious way

having a graceful and stylish quality that is not loud or flashy

showing amusement in a subtle, non-obvious way

to be seated without moving or making noise

to talk at a low volume

to utter words at a low volume

to walk without making much sound

to speak very softly, using one's breath without one's vocal cords

to make the sounds of laughter at a low volume

to shed tears with little or no sound