The art of sound pictures (1930)

226 THE ART OF SOUND PICTURES the different voices. The electrical connections from all of these different microphones are led into the soundproof room, usually called the monitor room. Here the different microphone currents are brought together through an electrical instrument known as the mixer. In the monitor room sits a sound monitor, who mixes the currents from different microphones in such a way that the best possible sound effects are produced. This man makes an effort, by manipulating the mixer, to equalize the volume of the voices of different actors, or to differentiate them as may be required by the scene enacted. Also, if an orchestra is playing simultaneously on the same set, the microphones register the orchestration, and this is also regulated through the mixer, so that the musical sounds do not drown out the dialogue and other necessary sound effects. The monitor has a receiver connected to the microphone circuit, and he can actually hear the sounds from the stage in precisely the same manner that the motion picture audience will ultimately hear these same sounds in the theater. One or more dialogue rehearsals are usually held on the stage before the picture and sound recording apparatus are interlocked. The monitor then reports to the director by telephone or loud speaker whether or not the voices of the different individuals on the stage are recording properly. If one is too loud, or if another is too far from the microphone, these faults are corrected before the scene is actually shot. After the preliminary tests are made, the director, or one of his technical assistants, calls “Interlock.” This order is transmitted to the sound room over a special telephone, and the necessary connections are made by the