A study of frequency fluctuations in sound recording and reproducing systems

The first part of the paper discusses the occurrence of unwanted Actuations of frequency in sound recording and reproducing systems and considers methods of measuring these fluctuations in disc-recording systems. A particular procedure is discussed in detail and new apparatus that has been developed for these measurements is described. It has been found that frequency fluctuations vary in magnitude in a random manner, and the second part of the paper indicates how useful information may be extracted from the highly complex data that result from continuous measurement. The statistical properties of the variations of magnitude have been found to be in accordance with theory developed for analogous electrical systems, and examples are given of a number of practical cases in which statistical analysis has enabled the causes of frequency fluctuations to be identified and appropriate action to be taken.