Sealed Thin-Multi-Layer Sound Absorber

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, in particular in the engine region, or the under body regions, or the wet area of doors of automotive vehicles, comprising at least three layers:

• a first layer being impervious to contaminations and having an area weight of 20-100 g/m2,
• a second layer being open pored or open celled, and exhibiting an air flow resistance Rt in the range of 250<Rt<2500 Ns/m3,
• a third layer being porous and in particular consisting of an open pored non-woven fibre layer or an open celled foam layer and having a thickness of 2-30 mm and an area weight of 50 to 1000 g/m2,
• whereby the first layer is designed to seal the other two layers against any exterior contamination, wherein the second layer has a thickness of 0.1-1.5 mm, in particular of 0.1-0.5 mm, and has a weight per unit area of 15-250 g/m2, in particular of 25-100 g/m2.