ACOUSTIC ENCLOSURE Russian patent published in 2018 - IPC E04B1/82 

FIELD: acoustics.

SUBSTANCE: invention relates to industrial acoustics, particularly, to broadband noise suppression, and can be used in all branches of the national economy in noise suppression of production equipment by sound absorption method. Acoustic enclosure contains a smooth and perforated surfaces, between which a multi-layer sound-absorbing structure is placed. Enclosure is made in the form of a rigid and perforated walls, between which there are two layers: sound-reflecting layer adjoining rigid wall, and sound-absorbing layer, adjoining perforated wall. Herewith a layer of the sound-reflecting material is made of a complex profile consisting of uniformly distributed hollow tetrahedra, allowing to reflect the sound waves that fall in all directions. Perforated wall has the following perforation characteristics: holes diameter – 3÷7 mm, perforation percentage 10 %÷15 %, wherein the shape of the apertures can be made in the form of apertures of a circular, triangular, square, rectangular or diamond-shaped profile, herewith in case of non-circular holes, the maximum diameter of the circle inscribed in the polygon should be considered as the nominal diameter. As sound-absorbing material, a porous noise-absorbing material is used, and porous mineral piece materials also can be used, herewith the surface of fibrous absorbents is treated with special porous air-permeable paints, for example "Acutex T", or covered with air-permeable fabrics or non-woven fabrics, for example "Lutrasil".

EFFECT: improving the efficiency of noise suppression by expanding the frequency range and secondary absorption of sound waves reflected from the absorber.

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