FIELD: acoustics.
SUBSTANCE: invention relates to industrial acoustics and can be used for machine drive noise reduction, lining of manufacturing facilities and in other sound-absorbing structures. Technical result is achieved by the fact that the objects in a silenced chamber acoustic characteristics studying method is that in the silenced chamber, in which the falling on the walls sound from the test object is absorbed, the test object is placed on the floating floor, at that, the silenced chamber is placed in the separate building with foundation, walls, ceiling, inside which, on the autonomous foundation, placing its walls, floating floor, on which the object to be tested and the light ceiling are installed, at that, the silenced chamber is hermetically lined on all sides with the newly developed sound-absorbing element to be tested, at that, the sound power level Lp of the test object is determined according to the average sound pressure level Lav measurements results on its measuring surface, for which the hemisphere S area is taken, at that, the studied noise absorbing nontransparent element is made with resonant inserts and contains smooth and perforated surfaces, between which the complex shaped sound-absorbing material layer is arranged, which is alternation of solid and hollow sections, wherein the hollow sections are formed by prismatic surfaces in the cross-section having a parallelogram shape, which inner surfaces have toothed structure, at that, teeth tops face inside the prismatic surfaces, and the prismatic surfaces ribs are secured on smooth and perforated walls, respectively, wherein the hollow sections cavities are filled with the sound absorber, and between the complex shaped sound-absorbing material layer smooth surface and solid sections, as well as between the perforated surface and the solid sections the resonant plates with resonant inserts, which function as the “Helmholtz” resonators necks are arranged, and located between the complex shaped sound-absorbing material layer perforated surface and solid sections, resonance plate with resonant inserts is made box-shaped, upper surface of the plate is adjacent to the solid sections of the layer of sound absorbing material, the angles of the side faces are fixed to the perforated surface, and its lower surface facing the perforated surface is set in relation to it with a gap necessary for placing resonant inserts that perform the functions of throats of the Helmholtz resonators.
EFFECT: technical result is increase in the new sound-absorbing elements under investigation acoustic characteristics noise attenuation efficiency measuring accuracy.
1 cl, 2 dwg
