The Acoustics of Enclosed Spaces

Abstract

THE acoustics of enclosed spaces intended to hold large audiences is now receiving attention, and it is recognised that good conditions for distinct hearing can be obtained only by eliminating the reverberation due to reflection from the walls. Owing to the high velocity of the transmission of sound in nearly all solid bodies, the angle at which total reflection begins is small; for oak wood it is about 6°, and for glass as low as 3°. Unless the wave-front is therefore very nearly parallel to a wall it cannot penetrate and is sent back into the room. The simple and partially effective method of deadening the reverberation by covering the walls with a highly porous material, or woven stuffs, is difficult to apply in large spaces, and a more hopeful solution of the problem seems to me to lie in the discovery of a substance that can be used for the exterior lining of walls and has a velocity of transmission not far different from that in air.