Sound absorbing laminate structure useful for noise reduction

摘要

A sound absorbing structure (I) comprises a low density layer (II) with two fibrous layers (III) and has a surface density of 0.5-1.5 kg/m<2>. The fibrous layers are produced from synthetic thermoplastic fibres with a diameter of 3-40 microns and length of 10-100 mm. Another layer (IV) of higher density is formed on the low density layer and has a density of 1-10 kg/m<2> and is formed of a polymer material that is impermeable to air.