US Patent 7537818 Sound absorptive multilayer articles and methods of producing same

Acoustically absorptive carpeting includes a primary layer of fibrous material with yarn tufts extending outwardly therefrom and a secondary layer of thermoplastic material that forms a carpet backing. The carpet backing is rendered porous. A substrate of porous material is attached to the carpet backing. The substrate includes a layer of fine fibrous material attached to a layer of coarse fibrous material. The layers of fine and coarse fibrous material each have respective different acoustic impedances. The layer of coarse fibrous material has fibers in an open, loose configuration. The carpet backing is bonded to the layer of coarse fibrous material with a thermoplastic adhesive material such that the thermoplastic adhesive material encapsulates individual fibers of the layer of coarse fibrous material without extending therebetween.