Laugh Track

How did Douglass originally invent the prototype for the Laff Box?

According to his wife Dorothy, Douglass would bring home tapes of television shows and then pore over them for hours and hours in his living room, finding and isolating the precise audience reactions he wanted. He spliced together tapes into spools—essentially tape loops. There was a keyboard for this machine, and each key was connected to a separate tape loop. At the bottom was a pedal that would either increase the volume or fade it out. So, really, it was like playing a musical instrument. And Charles Douglass was a virtuoso at the keyboard.

http://blog.theparisreview.org/2010/07/20/canned-laughter-ben-glenn-ii-television-historian/