ACHIEVEMENTS IN ACOUSTICS

"Muffling Office Noises" is the subject of an article by D. V. Casey in the March number of "System," in which he tells of the work of Dean Wallace C. Sabine, head of the Graduate Schools of Applied Science at Harvard, and the foremost American authority on architectural acoustics. Thousands of employers are confronted with the problem of eliminating noise in their offices, for they have found that it consumes strength and attention, and diminishes the efficiency of employees. The question has been solved by Dean Sabine, who, in 1895, began a series of experiments to determine the sound-absorbing qualities of various types of walls, floors, furniture and their coverings. The important result was the discovery that hair felt, when applied to the walls and ceilings, would practically destroy echoes or reverberations of all ordinary sounds, and thus reduce the total volume. Other fabrics, it was found, would absorb sound in lesser degrees.

To keep the advantages of the open office, and yet to cut down its drawback of noise is the problem which business men and scientists have been trying to solve for several years. Consequently the results of Dean Sabine's repeated experiments have been noted by many large industries and banks over the country. In one typical instance, the general offices of a Chicago packer employing four hundred were turned from bedlam into workrooms of more than usual quiet.

This treatment of walls and ceilings to eliminate noise, however, has passed the experimental stage. Besides the Chicago offices, there are at least seven other similar installations--to say nothing of the theatres, churches and courtrooms where hearing conditions were bad until enough absorbing material was introduced to correct them. Correcting the acoustics of a theatre is a parallel operation to eliminating noises in an office; in both cases it is the echoes or reverberations which make the trouble and which must be destroyed.

Laying down the rule that "the average loudness of a sound in a room is proportional inversely to the absorbing power of the material in the room," Dean Sabine has made careful experiments to determine the absorption value of the common forms of construction used in office walls and movable partitions. He has established the fact that a square yard of felt of a given thickness will absorb a certain amount of noise, and that if there is an overplus of noise, one must simply put up a corresponding area of sound-proof blanket. He has produced a long-fibre product of felt, designed to secure strength without losing absorbing power. The general result over the country has been the elimination in many cases of private offices, and the creation of large, single, office rooms, the ceilings and walls of which are treated with the new material. The great problem of excessive office noise as an important factor against office efficiency and costs has been solved. Dean Sabine has shown that noise can be controlled and reduced by scientific treatment.