Try this app. https://play.google.com/store/apps/details?id=com.jakedyme.soundtrigger. It'll either stop the noise, or make you feel good about life knowing that you're annoying them as much as they're annoying you.
Just get an old phone or android device, set it up next to the fence, or close...
I agree, I've worked in restaurants and pizza delivery, both of which SURVIVE off the tips. Its a disgusting system and should never be encouraged. As soon as an institution start to do it, their wages systematically drop to zero. The reason they get away with it is because people tip, so...