Theory of the absorption of sound by compressible walls with a non-porous surface-layer

✍ Scribed by C.W. Kosten; C. Zwikker

• Publisher: Elsevier Science
• Year: 1941
• Weight: 870 KB
• Volume: 8
• Category: Article
• ISSN: 0031-8914
• DOI: 10.1016/s0031-8914(41)90047-2

✦ Synopsis

Sound absorbing materials with a non-porous surface-layer possess great advantages over the usuall well-known porous materials. These advantages are related mostly to their hygienic and decorative qualities.

This kind of material, therefore, is already used in practice, the physical basis of the absorption, however, remaining often unknown.

It appears from theory that a low specific weight and a small modulus of elasticity are conditional for obtaining a strong absorption. These conditions are satisfied by layers of sponge rubber. The circumstances leading to the most favourable results have been examined and turn out to be as follows: the pores should be preferably such that the air inside is to some extent free to vibrate as an independent body. Big holes in the laver as well as the application of the material at some distance from the rigid wall appear, under certain circumstances, to influence the sound ahsorbing qualities favourably.