Man's physical universe








One can scarcely hear himself talk in many factories where machinery

of all kinds is creating a ceaseless din and clatter of squeaks,

rumblings, rattles, and hammerings. Modern warfare is characterized

by the sounds of airplane motors, machine guns, exploding bombs, and

heavy gunfire. The noise of streetcars, automobile horns, truck and

bus gears, automobile exhausts, traffic signals, the blare of radio

loud-speakers, and the cries of newsboys are so commonplace that a

city dweller may find it difficult to adjust himself to the relative quiet

of the countryside. While one may become so well adjusted to noises

that he cannot study without a radio playing, there is no question

concerning the nervous tension that is created by the continuous stimulation

of the nerves of the ear by unnecessary and disturbing sounds

which are called noise. Even music may be disturbing to frayed nerves.

One might almost say that one's social maturity can be judged by

the amount of unnecessary noise that he makes. It is only common

sense that the more noise there is, the louder one will have to talk and

the more penetrating automobile horns will have to be. Progress, as

far as sound in its relation to society is concerned, is represented by

campaigns, laws, and methods of reducing unnecessary sounds, rather

than the development of more and louder sounds. The radio loudspeaker

has given man a marvelous method of amplifying sound, but

the radio loud-speaker may become a public nuisance when employed

by people, young or old, who are thoughtless of the sound sensitivities

of other people.

This Section deals with the control of sound, which is the problem of

the science of acoustics.

The Intensity of Sound Waves May Be Increased by Resonance.

The intensity or loudness of a sounding body may be increased by

This principle can be illustrated by striking a

use of a sounding board.


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