Patent ID: 8863897

Claim:
A sound attenuating trim part, comprising: at least one insulating area having acoustic mass-spring characteristics and comprising: a decoupling layer; and at least one mass layer adjacent to the decoupling layer comprising: a porous fibrous layer; and a barrier layer located between the porous fibrous layer and the decoupling layer, wherein: the decoupling layer, the porous fibrous layer, and the barrier layer are all laminated together; and the porous fibrous layer, at least in the insulating area, is adjusted to have a dynamic Young's modulus (Pa) of at least approximately: 4 ⁢ ⁢ π 2 · 10 - 6 · t p · v 2 · AW b · AW p 3 + AW p 2 12 AW b + AW p ; and where: AW b is an area weight (g/m 2 ) of the barrier layer, AW p is an area weight (g/m 2 ) of the porous fibrous layer, t p is a thickness (mm) of the porous fibrous layer, and v (Hz) is a radiation frequency of at least 3000 (Hz), and the barrier layer has an area weight of at least 400 (g/m 2 ).