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AssigneeRoth Freres, S.A.
InventorAlain Manigold
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A panel absorbing acoustical energy at low, medium and high frequencies, particularly at frequencies ranging from 400 Hz to 5,000 Hz, is essentially constituted by a plate (1) of semi-rigid foam with open communicating cells and by a layer (2) of bonded fibers or by a flexible cellular material. The assembly acts according to a mass-spring principle. The plate (1) of semi-rigid foam with open communicating cells constitutes the mass of the assembly functioning according to the mass-spring principle, while the layer (2) of bonded fibers or of flexible cellular material constitutes the spring of this assembly. The foam comprising the plate (1) is preferably a semi-rigid polyurethane foam of a density ranging from 20 kg/m.sup.3 to 50 Kg/m.sup.3, of a thickness comprised between 5 mm and 15 mm and whose permeability to air is comprised between 5 liters per minute and 45 liters per minute for a specimen 80 mm in diameter. The layer (2) constituting the spring has a stiffness ranging from 0.007 MPa to 0.05 MPa and a thickness ranging from 4 mm to 10 mm.
A panel absorbing acoustical energy at low, medium and high frequencies ranging from 400 Hz to 5,000 Hz, which comprises a plate (1) of semi-rigid foam with open communicating cells and a layer (2) of bonded fibers or a flexible cellular material superposed on and secured to said plate (1) to form an assembly, the assembly acting according to a mass-spring principle, or wherein the foam of the plate (1) is a semi-rigid polyurethane foam of a density ranging from 20 Kg/m.sup.3 to 50 Kg/M.sup.3, of a thickness ranging from 5 mm to 15 mm and whose permeability to air ranges from 5 liters per minute to 45 liters per minute for a specimen 80 mm in diameter.
A panel absorbing acoustical energy at low, medium and high frequencies ranging from 400 Hz to 5,000 Hz, which comprises a plate (1) of semi-rigid foam with open communicating cells and a layer (2) of bonded fibers or a flexible cellular material superposed on and secured to said plate (1) to form an assembly, the assembly acting according to a mass-spring principle, or wherein the layer (2) constituting the spring and formed by a sheet of bonded fibers or by a flexible cellular material, has a stiffness ranging from 0.007 MPa to 0.05 MPa and a thickness ranging from 4 mm to 10 mm.
A panel absorbing acoustical energy at low, medium and high frequencies ranging from 400 Hz to 5,000 Hz, which comprises a plate (1) of semi-rigid foam with open communicating cells and a layer (2) of bonded fibers or a flexible cellular material superposed on and secured to said plate (1) to form an assembly, the assembly acting according to a mass-spring principle, or wherein said layer (2) is 40% to 80% of polyester fibers having a titre ranging from 4 decitex to 20 decitex, and 20% to 60% of thermofusible fibers having a titre ranging from 4 decitex to 20 decitex.
Dependencies are inferred from the claim text.