Combating phone theft

I see a lot of posts here discussing how to lessen being a target of phone theft. But have we considered trying to combat it? My thought is, we could make decoy phones that are really powerful speakers or trackers. So when they are removed from where they are suppose to be (such as a pocket) in a period of time they emit an amber alert level of noise. That way the thief has to drop the loot. The noise might be annoying at a music show but I’m sure it will drop phone thrift quickly and make it an over all more enjoyable experience.

Has this been done before? What would be required to make this happen? Could the hosting event sponsor the build and distribution of these devices?