Ultralight soundproof material

Abstract

A sound insulator of the invention includes a sound absorption layerand an air-impermeable resonance layer, which are bonded to each other via an adhesive layer. The sound absorption layerhas a thickness in a range of 5 to 50 mm and an area-weight of not greater than 2000 g/m. The sound absorption layerhas a two-layer structure of a high-density sound absorption layerand a low-density sound absorption layer, which have different densities. The high-density sound absorption layeris bonded to the air-impermeable resonance layervia the adhesive layerand has a density in a range of 0.05 to 0.20 g/cmand a thickness in a range of 2 to 30 mm. The low-density sound absorption layeris bonded to the other face of the high-density sound absorption layer, which is opposite to the air-impermeable resonance layer, via an adhesive layerand has a density in a range of 0.01 to 0.10 g/cmand a thickness in a range of 2 to 30 mm. The structure of this sound insulator effectively reduces a noise level in a voice-tone frequency band, especially in a high frequency domain, thereby efficiently enhancing the clarity of conversion in a vehicle interior.