SOUND ABSORBING AND VIBRATION DAMPING MATERIAL

摘要

PROBLEM TO BE SOLVED: To provide a sound absorbing and vibration damping material which is higher in sound absorption effect for low frequencies below 300 to 400 Hz in particular than that in the prior art and can decrease solid propagation sounds and vibrations as compared with that in the prior art for all of frequencies. SOLUTION: This sound absorbing and vibration damping material 1 is formed by gradiently varying the fiber density of a fibrous assemblage 2 coated with viscoelastic bodies on the surfaces of respective fibers in the thickness direction. The effect is higher if a vibration damping sheet 3 consisting of the viscoelastic body is laminated on the sound source side and a vibration damping sheet 4 consisting of the viscoelastic body on the rigid wall side. The vibration damping sheet 3 consisting of the viscoelastic body on the sound source side may be formed of a closed cell foam consisting of the viscoelastic body or as a thin metallic film layer.