Abstract: Airborne resonance buildup (in directions parallel with and/or at acute angles to the first and second major skins or panels of enclosed cavities) is damped by locating anisotropic porous damping materials within the cavity between the first and second major skins or panels of the cavities. In one preferred embodiment, one or more anisotropic fibrous blankets are located between the skins of a cavity with the fibers of the blanket(s) lying in planes generally perpendicular to the first and second skins and parallel to one pair of the sidewalls of the cavity.

Abstract: A sound absorption laminate comprises a porous insulation substrate, such as, a thermoplastic glass or polymeric fiber blanket or a foamed polymeric resin sheet and a facing sheet with a high air flow resistance. The facing sheet is adhered to a surface of the porous insulation substrate to augment the acoustical properties of the substrate. With the facing sheet the air flow resistance of the laminate is greater than the air flow resistance of the substrate and the laminate exhibits a higher sound absorption coefficient than the sound absorption coefficient of the substrate. Thus, the laminate exhibits better sound absorption properties than the substrate and is suitable for sound absorption applications for which the substrate alone would not be suitable.