PURPOSE: To enable the sound absorbing material to have sufficient acoustic absorptivity in a wide range of a lower frequency area by laminating plural powder layers by interposing a porous layer between each of them, and forming the powder layer by fibrous powder and non-fibrous powder.
CONSTITUTION: The sound absorbing material 1 takes a laminated form whose total thickness is about 30mm, on which four powder layers 4, and three porous layers 5 interposed between each powder layer are laminated alternately. Each powder layer 4 consists of mixed powder in which silica powder whose average grain diameter is 150μm and an assembly (80μm average grain diameter) of silicon carbide whiskers whose average grain diameter and average length are 0.5μm and 35μm, respectively are mixed in a volume ratio 1:1, and its thickness is about 5mm. Also, the porous layer 5 consists of glass wool, and its thickness is about 3mm.
OKUDAIRA YUZO
KURIHARA YOSHITAKA
