You know what Batman sounds like. Same for Sponge Bob, Bugs Bunny, Bender, and a zillion other characters in cartoons, games and movies. These are the people who make them come to life, in the new documentary I Know That Voice.

The doc features voice acting superstars like Kevin Conroy (BATMAN! KEVIN CONROY IS BATMAN), June Foray, and John Di Maggio. There are loads of voice acting professionals talking about the actual science that goes into voicing characters. Slow it down to make a character dumber. Change a pitch here or there to make a character an adult—or an irresponsible almost-adult. It's really fascinating stuff. The documentary's still in development, but there's actually a bunch of cool stuff packed into this four minute trailer.