Excerpt from Journal of the Society of Motion Picture Engineers, Vol. 46: January, 1946 Summary. - Variable density sound film recording is subject to intermodulation distortion in the low -frequency band which extends from the lower limit of the audible spectrum toward zero, but not to zero frequency. This distortion is the result of the Bromide Drag phenomenon and is in the nature of exorbitant gamma. Cor rections may be made for gamma at any point in this exorbitant range, but only at the sacrifice of correct gamma for other frequencies. The popular intermodulation method of distortion analysis uses 60 cps as a low frequency component, which frequency lies in the exorbitant band. The data ob loined thereby are representative of the exorbitant conditions and are misleading if they are taken to represent the entire recorded frequency spectrum. The delta-db method of distortion analysis gives data representative of conditions in which the low-frequency component is zero frequency. The analysis shows, however, that the data are also representative of frequencies above the exorbitant band and, therefore, represent the general recorded frequency spectrum except for the exorbitant band. Optimum processing specifications should be based upon data representing both conditions - outside the exorbitant band, as indicated by the delta-db method (zero frequency), and inside the band, as indicated by the intermodulation method using several frequencies around 60 cps. Either method may be used alone for processing control data after all conditions have been determined and are known to remain constant. Practice has substantiated the merits of the principles expounded here. About the Publisher Forgotten Books publishes hundreds of thousands of rare and classic books. Find more at www.forgottenbooks.com This book is a reproduction of an important historical work. Forgotten Books uses state-of-the-art technology to digitally reconstruct the work, preserving the original format whilst repairing imperfections present in the aged copy. In rare cases, an imperfection in the original, such as a blemish or missing page, may be replicated in our edition. We do, however, repair the vast majority of imperfections successfully; any imperfections that remain are intentionally left to preserve the state of such historical works.