Analysis of Sound Waves

Most sounds consist of a spectrum of frequencies of various intensities. The distribution of the frequencies and intensities determines the quality of the sound. The spectrum may remain fairly constant in time, or it may go through rapid changes. Sound analysis is the process by which the various components of the spectrum are detected and measured. A complete analysis should furnish the frequency and amplitude of each component as well as its phase relatively to the other components, at a given instant of time. If the spectrum changes in time, a complete analysis should be made at intervals throughout the duration of the sound, the lengths of the intervals being determined by the rate at which the spectrum is changing. — For purposes of analysis sounds may be grouped into four classes: (1) sounds that may be maintained at constant frequency, constant intensity, and unvarying quality for a period long enough to carry out the analysis; (2) sounds that are essentially transient in nature; (3) sounds that may be maintained constant, on the average, but whose frequency, intensity, and quality vary periodically within this time; (4) sounds that are entirely random in form but are continuously maintained. The first two groups of sounds require different methods of analysis. The third group in certain instances may be analyzed by the methods used for class 1, whereas in others the method used for class 2 may be necessary. Sounds of class 4 may be analyzed by all methods capable of analyzing sounds of class 1 with one exception. — Instruments for analysis may be grouped into five classes: graphic, resonance, heterodyne, stroboscopic, and diffraction analyzers. The operation of each type of instrument is briefly discussed and the suitability of each for analyzing the various classes of sounds is brought out. Examples of analyses performed by the various methods are presented.

Print ISSN

0097-5834

Published

1936-10

Content type

Original Research

DOI

10.5594/J14740