Microphotometric Analysis of Movietone Sound Records

Abstract

IN a letter published in a recent number of NATURE (July 19, p. 93), Dr. Louis V. King announced a method of microphotometric analysis of movietone sound records. Evidently Dr. King has overlooked that this method was described by me seven years ago in a paper, “Photographic Recording and Photoelectric Reproduction of Sound”, published in the Transactions of the Society of Motion Picture Engineers, No. 16, 1923. On page 113 of the paper, Fig. 24 serves to illustrate this method of sound analysis. A comparative study of analysis of sound records by means of Moll's thermoelectric microphotometer and Koch's photoelectric microphotometer was made in 1927. A brief report thereof was published in the Bulletin of the American Physical Society, vol. 4, p. 2, April 1929, and also in the Physical Review, vol. 33, p. 1094, 1929, under the title “Application of Microphotometers for the Analysis of Photographic Sound Records”.