Sound Analysis

Abstract

Instruments for sound analysis may be grouped into five classes—graphic, resonance, heterodyne, stroboscopic, and diffraction analyzers. The operation of each type of instrument is briefly described and examples of analyses performed by the various methods are presented. From the point of view of analysis sounds may be classified roughly into four groups: (1) Steady state sounds or sounds which may be maintained at constant fundamental frequency, constant intensity and unvarying quality for long enough to carry out the analysis. (2) Sounds which are essentially transient in nature. (3) Sounds which may be maintained constant on the average but whose frequency, intensity and wave form are modulated at a constant frequency. (4) Noise, or sounds which are entirely random in form but which are continuously maintained. The sound spectra corresponding to each group are described and the application of the various types of instruments to the analysis of these spectra is discussed.