A Device for Automatically Controlling the Balance between Recorded Sounds
William A. Mueller · Journal of the Society of Motion Picture Engineers · 1935
A re-recording method is described in which the dialog automatically controls the recorded level of the background effects or music, the dialog depressing the level of the effects or music from the normal value. This is accomplished by using the rectified dialog currents to control the grid-bias of a variable-mu tube. Its use results in greater intelligibility and realism in sound pictures.