Patent ID: 8158246

Claim:
An ultra-light sound insulator, comprising: a sound absorption layer that is light in weight and has a thickness in a range of 1 to 50 mm, the thickness varying from one region to another in a range not greater than 50 mm, and a density in a range of 0.01 to 0.2 g/cm 3 ; and an air-impermeable resonance layer in the form of a film having a thickness in a range of 10 to 200 μm that is bonded to said sound absorption layer via an adhesive layer and has an area-weight of not greater than 200 g/m 2 , wherein an adhesion strength of said adhesive layer against said sound absorption layer and said air-impermeable resonance layer is set in a range of 1 to 20 N/25 mm under conditions of a peel angle of 180 degrees and a peel width of 25 mm, an adhesion area of said adhesive layer is 50 to 100% of a whole interface between said sound absorption layer and said air-impermeable resonance layer so that resonance due to a total mass of said air-impermeable resonance layer and said sound absorption layer occurs in addition to membrane resonance of said air-impermeable resonance layer, and said sound absorption layer is adapted to face to a vehicle body panel, while said air-impermeable resonance layer is adapted to face to a vehicle interior.