Abridgment of the electrical engineering of sound picture systems

The paper describes the technique and apparatus of sound picture recording and reproduction, with emphasis on their electrical engineering aspects. The various steps in the processes of disk and film recording as they take place in the Western Electric systems are outlined. Microphone placements, sound insulation, monitoring and mixing, and the circuits for amplifying currents and distributing them to recording machines are discussed. This is followed by a description of the disk and film recording machines. The changes which have been required in theater equipment to provide for the reproduction and projection of sound in synchronism with motion pictures are outlined. Some of the laboratory developments and studies out of which recording and reproduction methods have grown are given brief mention.