The simplest way is to throw in a bar of soap.
Another way is to sit near by the PA system with a CB radio or an FM transmitter for a wireless microphone and broad cast until a buddy inside with a cell phone lets you know if your voice is coming over the sound system.
I learned this lesson the hard way. My band was playing near a road where truckers were using their CB radios and their broadcast were coming over our sound system and our guitar amps.
The broadcast single from a CB radio can often get picked up by the building's wiring and find its way to the PA system's amplifier.
A wireless microphone can broadcast directly to a receiver. But it seems that most of the time the mics at MAGAt rallies are NOT wireless.
Audio - Picking up HAM or CB talk over PC speakers ...
Jan 10, 2011 · The CB radio signals you hear in your speakers are being picked up in all the wiring in the house, you can't stop that, but you can stop it getting into the TV, PC or radios, at the point where ...
