ways teams are stealing signals and eradicating those cheats. In the case of the Astros, they were sending signals to the batter by banging something. There are only a limited number of ways you can signal the pitch to a batter (sound being one of them). If you hear a weird sound that is unique enough to be singled-out by a batter, and you hear it repeated frequently enough, you should be able to identify it if you're looking for it.