GREAT simplification of understanding and unusual results in production often follow new approaches to old problems. When noise problems are stated in terms of the familiar physical units of pressure, velocity, weight, and stiffness, basic ideas are obtained which can be applied directly to practice. In this way, most of the mysteries and the contradictions of noise problems are eliminated.
In their elements, noise problems involve only simple physical factors which are understood easily, and which can be measured with available equipment. Similarly, the solutions involve the straightforward application of known and definite engineering principles.
Although simple in their elements, most practical noise problems are very complex because of their combinations. Often much ingenuity is required to measure the physical characteristics of the noise which determine the human impressions obtained from it. Such determinations can be made by proper modification of the attack and the measuring equipment, and are the key to successful noise reduction.
This paper gives a classification of the various means of quieting, and outlines the technique of applying them to production. The viewpoint is quite different from that usually employed, and the practicability of the method is illustrated by examples of actual jobs.
