Patent ID: 7677358

Claim:
A multi-layer sound absorber to be mounted on a carrier layer or a frame for reducing the exterior and interior noise caused by the engine of an automotive vehicle or by its rolling/rotating wheels, whether in the engine region or the under body regions or the wet area of doors of automotive vehicles, comprising: a first layer being impervious to contaminations and having an area weight of 20-100 g/m 2 , a second layer being open pored or open celled, and exhibiting an air flow resistant R t in the range of 250<R t <2500 Ns/m 3 , the second layer having a thickness of less than one millimeter and a weight per unit area of 15-250 g/m 2 , a third layer being porous and consisting of one of an open pored non-woven fibre layer and an open celled foam layer and having a thickness of 2-30 mm and an area weight of 50 to 1000 g/m 2 , the first layer surrounding and sealing the other two layers against any exterior contamination.