Aircraft cabin interior noise treatment

Abstract

A noise reducing blanket for use in an aircraft cabin for reducing acoustic noise transmission from an aircraft airframe to a cabin interior. The blanket includes a mass barrier portion, a foam portion having at least one cavity formed in it, and a vapor barrier which is disposed about the foam portion The mass barrier portion includes a plurality of vinyl layers that are attached to one another at spaced apart locations. The spaced attachment allows the layers to move substantially independently from one another. The layers are preferably attached to one another by stitching that includes between approximately three to five stitches per inch. There are preferably at least two layers in the mass barrier portion, and, more preferably, between 2 and 4 layers in the mass barrier portion. The cavities in the foam portion are designed to increase the noise absorptive properties of the blanket. Preferably at least one of the dimensions of the cavities in the foam portion is approximately ¼ the wavelength of the dominant noise frequency to provide a resonant chamber within the foam portion. In one embodiment of the invention, the foam portion is attached to the mass barrier portion with an adhesive. In a second embodiment of the invention the foam portion is mounted to the aircraft separate from the mass barrier portion.