SPHERICAL ACOUSTIC ABSORBER Russian patent published in 2018 - IPC E04B1/84 G10K11/16 

FIELD: acoustics.

SUBSTANCE: invention relates to means of reducing noise in industrial and transport facilities. In a spherical acoustic absorber, containing acoustic absorbers of active and reactive types, placed on a rigid frame, the frame is made of two parts, a lower, reactive part is made in the form of a spherical shape with an internal congruent spherical resonant cavity formed by a rigid continuous spherical shell, equidistant an outer perforated spherical shell, connected to an upper, active part, which is made in the form of a rigid perforated cylindrical shell with a perforated cover and a solid base, wherein the cavity of the cylindrical shell is filled with sound-absorbing material, and the connection of the upper and lower parts of the acoustic absorber is made by means of an elastic damping element, which allows to damp high-frequency oscillations, while an element is hinged to the perforated cover of the perforated cylindrical shell, with the help of which the frame is attached to the required object, for example, workshop ceiling, and the spherical resonant cavity of the reactive part of the frame is rigidly connected by at least one sleeve with an axial hole serving as a neck of a Helmholtz resonator with an outer perforated spherical shell, and the space between them is filled with a sound absorber, while a rigid porous noise-absorbing material is used as a sound-absorbing material for filling a cavity of rigid perforated cylindrical shells, for example, cermet, or shell stone with a degree of porosity in the range of optimum values of 30…45 %, or crumb from hard vibration damping materials, for example, elastomer, polyurethane, or plastic compound of “Agat”, “Antivibrite:, “Schwim” type, where the size of crumb fractions is in the optimum range of values of 0.3…2.5 mm, or as a acoustic absorbent for filling a cavity of rigid perforated cylindrical shells, a porous acoustic absorbing ceramic material having a packed density of 500÷1,000 kg/m³ and consisting of 100 parts by weight of perlite with the particles diameter of 0.5÷2.0 mm, 100÷200 parts by weight of one or more sintering materials and 10÷20 parts by weight of binding materials.

EFFECT: technical result is an increase in the efficiency of noise attenuation at high frequencies by introducing into a unit acoustic absorber of cavities for Helmholtz resonators that increase efficiency at high frequencies.

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