As television moved out of the laboratory and into regular broadcasting schedules during the decade of the 1930s, it was obvious early on that the “hand signal” methodology used in radio broadcasts for communication between a show’s director and performers in the studio wouldn’t work. Television’s glaring lights and much larger studio spaces made such visual communication either very difficult or impossible.
As a solution, early TV broadcasters cobbled together their own intercom systems from available telephone company technology (switchboard operator headsets and carbon microphones) to enable “party line” communications among all crew members.
