I’ve heard that there are ways of “jamming” bugging devices so that no one can hear what you’re saying. This doesn’t mean jamming the radio signals. Supposedly, something called “zero-beating” renders sound inaudible to microphones, but not to the human ear. It’s supposed to work even on stuff like shotgun microphones and laser listeners. Is such a thing real?
This is active noise reduction and is utilized to reduce noise at key points. The idea is that you produce a noise signal 180 deg out of phase with the existing noise, and the end result is a VERY limited area of near no noise. The problem is that it only affects a specific location, rather than, say, a whole room, and it affects human hearing as well as listening devices.
The ear acts much like a microphone, and anything that affects one will affect the other (unless you start using things like EM generators which whould only affect local listening devices rather than those at a range). You could use this active control to render a known bu location useless, but not any bugs in the area.