High Quality Content by WIKIPEDIA articles! Structures of this type were in use in the motion picture industry before the advent of sound recording. Early stages for silent movies were built either as a three-wall open-roof set or with large skylights until electric lighting became powerful enough to adequately expose film. With electric lights, enclosed stages were built in Hollywood and rapidly converted to sound stages with many matresses placed on the walls. With the coming of the talkies in the late 1920s, it became necessary to enclose and fully sound-proof the stages to eliminate noise and distractions from outside. Buildings without soundproofing are still referred to as silent stages, and can be used where the dialog and other sounds are recorded as a separate operation, usually by the principal actors doing a synchronized voice over a working "cut" of the film or specialized language actors doing a secondary language dubbing.