soundlessactivity
nounUK /ˈsaʊndləs ækˈtɪvəti/
US /ˈsaʊndləs ækˈtɪvəti/
Something you do without making any noise.
Reading in the library is a soundless activity.
OTHER MEANINGS
2. A job or action done in complete quiet so no one hears it.
Tiptoeing past the sleeping baby was a soundless activity.
3. Any movement or work that produces no sound at all.
The robot vacuum is designed for soundless activity at night.
4. A calm, silent thing to do that keeps you busy.
Drawing in her notebook was her favorite soundless activity.