THE desirability of measuring sound by soundmeter, rather than by listening with human ears, is expressed by the author, who states that soundmeter measurements indicate definitely just what components of noises must be reduced and also just what has been accomplished by any given change. Usually, they may be taken so as to indicate the part responsible for the noise, and even the nature of the defect. He then considers some fundamental characteristics of human ears and of various sounds.
The apparent inconsistencies of the mass of data obtained from soundmeter measurements made in connection with practical noise-problems are explained, and the physical problem of what soundmeters measure is presented, together with a discussion of the subject of sound pressure and the use of the decibel scale of sound measurement which includes definitions of the various terms and units employed.
The psychological problem, that is, the interpretation of sound measurements in terms of ear sensations, is presented at length and followed by a summary. The practical problem, that is, the technique of noise reduction, is analyzed also, quieting methods are suggested under seven specific headings, and it is stated as a conclusion that sound measurements obtained with measuring instruments are an indispensable aid in achieving logical noise-reduction.