The Decibel in the Motion Picture Industry
Vincent C. Hall · Journal of the Society of Motion Picture Engineers · 1932
The development of the term “decibel” is outlined, and its convenience in measuring the characteristics of electrical circuits discussed. The relation of the decibel to photographic density is pointed out and illustrated by calculations of the effect of ground noise reduction devices. Finally, the values of acoustic power of common sources of sound are given as the levels in decibels based on various Reference points in use in the motion picture industry.