A.V.Kirjukhin*. V.Yu.Machnev, V.B.Stepanov SEVERAL STUDIES ON THE REDUCTION OF LOW FREQUENCY AIRBORNE NOISE EMERGING FROM THE CLOSED SPACE

The reduction of low frequency noise levels emerging out from the closed space is an actual problem for many domains of industry. The problem can not be solved by means of only the space walls soundinsulation increasing by virtue of the fact that the levels of sound energy within the space will increase in proportion to soundinsulati on. That is why the soundproofing structure should has a pronounced sound absorption as well. It is the sound absorption that enables to realize an increase in structure sound insulation without rise in sound energy level. Thus, the soundproofing structure should include some elements providing the heightened soundinsulation and a sound absorption layer which is responsible for sound energy absorption. If the thickness of sound absorption layer is rather great, this layer can combine the properties of sound absorber and sound insulator at the same time. Below are the physical models and conforming to it results of calculations and experimental study of some structures, which allow to outline the ways of rational projecting of low frequency noise control means.