Activation sounds play when either a switch or an object is operated.
Switch-Activated Sounds
Place a Switch somewhere in the map, and tag it [ActivationSound,Channel]. Every time the Switch is pressed, the ActivationSound will play. If you don't want the Switch to activate any effects, give the Channel a unique value. If the Channel is not given a value, the Switch will not function at all.
MUSICANDSFX-Activated Sounds
Place an M[StopSound,StartSound] within a functioning sector (this works with most effects). When the sector's function is activated, the sounds will play. StopSound and StartSound are the most common values, but not entirely consistent.