The room is divided into "sound" and "mute" zones.
All participants choose a simple song or a melody they can sing. Upon entering a "mute" zone, a
participant should switch to silent lip-syncing of the song and resume singing aloud upon walking into the "sound" zone
Variation: the room can be divided into zones of gradually changing volumes, from quietest to loudest.
Small groups of participants have to cross the room singing the song accordingly to the area they are in.
The challenge here is to carefully choose the volume of singing in each zone so that it doesn't get too loud
before the loudest area of the room is stepped into.