THE OTAGO DAILY TIMES FRIDAY, FEBRUARY 15, 1929. THE PSYCHOLOGY OF NOISE.

Otago Daily Times, Issue 20643, 15 February 1929, Page 8

THE OTAGO DAILY TIMES FRIDAY, FEBRUARY 15, 1929. THE PSYCHOLOGY OF NOISE.

We have referred in previous articles to the attention that is being given to the advisability of reducing the noises that are an undesirable accompaniment of our civilised life. A plea which is made in our correspondence columns this morning by a patient of the public hospital—a plea that should surely not be disregarded—induces us to revert to the subject. It is an intolerable thing that the rest of sufferers from illness should be disturbed by street noises, most intolerable because there is no reason at all why these noises, if they cannot be stopped altogether, should not be greatly abated. The grievance which exists because of them would be much lessened, it may be surmised, if energetic measures were taken to enforce

the motor regulations that are' now in force. The whole matter of the effect that is due to noises possesses points of interest which not so many years ago were very imperfectly apprehended. The investigation, for instance, by psychologists of the causes of fatigue in various occupations has thrown a certain light on several of the causes that determine the efficiency of workers. It has been clearly established that the proper alternation of work and rest periods considerably increases the output of industry. Dr Laird, director of the Psychological Laboratory of the Colgate University, United States, has, as the result of an inquiry into the relation between noises and industrial efficiency, already accumulated some valuable data which indicate plainly that the reduction of the noise of our civilised life would make industry more efficient. He states that, while in our present civilisatio" noises havfe been increasing by leaps and bounds, there is not much indication that they are going to decrease spontaneously.' He considers that the present type of building tends to prolong and transmit noises. Bare plastered or brick walls' reflect sounds better than a mirror reflects light. By the use of rugs, thick felt, or heavy velvet drapes on walls, reverberation would be greatly reduced; —the sound would be absorbed .and considerably lessened. It would be possible’, Dr Laird considers, to construct buildings so that sound-absorbing material could be placed in the walls. Very little attention has yet been given to this aspect of the construction of buildings. Dr Laird ascertained from experiment that when the noise in a test chamber was reduced 15 per cent, there was <a 5 per cent, increase of work done by expert typists and at the same time the bodily energy dissipated was 25 per cent. less. Scientists have long been .able to measure accurately the intensity of light, but it is only recently that it has been possible to * measure the intensity of sound. The Bell Telephone Laboratories invented the audiometer, which measures sounds on a scale running from 0 to 100. Some factories have a continuous noise of 85; subway trains measure 75 to 80. In the experiment with the typists, the noise measured about 50. The increase in the output was secured because the intensity of the unreduced noise was just above a critical level—: that is to say there was an intensity of sound that produced ilheffects. A further reduction of sound did not affect the output of work. As might be expected, a moderate amount of noise does not interfere with efficiency in work. '

The second finding in relation to the consumption of 25 per cent more bodily energy due to working under noisier conditions was determined by collecting the exhaled air and analysing it for oxygen consumption, production of carbon dioxide, and total volume. It is a scientific fact that typists working under noise exert increased pressure on the typewriter keys. But this is not the only indication of a waste of energy. Under noisy conditions energy is also dissipated by a general tenseness of all the muscles of the body. This is" the exact reverse of relaxation and is fatiguing and saps energy unnecessarily. The biological injury due to intense noises does not mainly consist in damage to the ear or auditory nerve, but rather to the fact that the noises are an inborn stimulus to cause the fear reaction. Common noises illustrate this fact in everyday experience. Examples are furnished in the shiver up one’s spine when a file squeaks; 1 the involuntary jump at the unexpected report of a pistol; the fatigue after a noisy railway journey. Some few people are affected only slightly by noises, but as a general rule intense or intermittent noises are prime instigators of the fear reaction and cause involuntary muscle contraction, besides affecting pulse rate, blood pressure, and breathing. A person who was being observed by a trained psychologist in the University of Michigan was sleeping near the street when a noisy motor car passed along. In this ease, which is of peculiar interest in view of the complaint which is made by our correspondent this morning, it was noted that though the subject did not wake, there was a distinct rise in his blood pressure. The conclusion to which these investigations lead, is that a reduction of noise in factories and other establishments would not only increase the efficiency of many workers, but also, by reducing nerve strain, benefit their health.