There's this technology to make people shut up because apparently it's hard to talk in the presence of your own speech being repeated with a split second delay. But here's a thought: we don't need a fancy-pants microphone and speaker gun to make it happen. We have microphones, speakers and computer processors in our pockets right now. All we need is an app to make this happen, assuming the speakers are loud enough. It should be pretty easy, in theory.
Mokalus of Borg
PS - Of course, theory and practice can be worlds apart.
PPS - And I have yet to write even a simple app.