Carroll Prat and his Laff Box

Charles Douglass was the man who developed laugh tracks for TV sitcoms. He built the Laff Box, a gadget he used to mix the appropriate audience reactions to "sweeten" the story. Audio engineer Carroll Pratt trained under Douglass, and later computerized the Laff Box, added stereo capability, and formed his own company. Watch Pratt editing a sitcom to enhance the laughter in this video. (via Boing Boing)