Sound absorbing structure using closed-cell porous medium

Abstract

A sound absorbing structure is constituted of a housing, a vibration member composed of a closed-cell porous material whose airflow rate is less than 0.1 dm 3 /s, and an air cavity formed inside the housing in the rear side of the vibration member. Alternatively, the vibration member is formed by laminating an open-cell porous material or an air-permeable member with the closed-cell porous material. The sound absorbing structure demonstrates a high sound absorption in a low frequency range due to the closed-cell porous material.

1 . A sound absorbing structure comprising:
 a vibration member composed of a closed-cell porous material; and   an air cavity formed in a rear side of the vibration member.   
     
     
         2 . A sound absorbing structure comprising:
 a vibration member composed of a closed-cell porous material and an open-cell porous material which are laminated together; and   an air cavity formed in a rear side of the closed-cell porous material.   
     
     
         3 . A sound absorbing structure comprising:
 a vibration member composed of a closed-cell porous material and an air-permeable member which are laminated together; and   an air cavity formed in a rear side of the closed-cell porous material.   
     
     
         4 . The sound absorbing structure according to  claim 1 , wherein an airflow rate of the closed-cell porous material is less than 0.1 dm 3 /s. 
     
     
         5 . The sound absorbing structure according to  claim 2 , wherein an airflow rate of the closed-cell porous material is less than 0.1 dm 3 /s. 
     
     
         6 . The sound absorbing structure according to  claim 3 , wherein an airflow rate of the closed-cell porous material is less than 0.1 dm 3 /s. 
     
     
         7 . A sound absorbent group including a plurality of sound absorbing structures, each of which is constituted of a vibration member composed of a closed-cell porous material, and an air cavity formed in a rear side of the vibration member. 
     
     
         8 . A sound absorbent group including a plurality of sound absorbing structures, each of which is constituted of a vibration member composed of a closed-cell porous material and an open-cell porous material which are laminated together, and an air cavity formed in a rear side of the closed-cell porous material. 
     
     
         9 . A sound absorbent group including a plurality of sound absorbing structures, each of which is constituted of a vibration member composed of a closed-cell porous material and an air-permeable member which are laminated together, and an air cavity formed in a rear side of the closed-cell porous material. 
     
     
         10 . A sound chamber including at least one sound absorbing structure, which is constituted of a vibration member composed of a closed-cell porous material, and an air cavity formed in a rear side of the vibration member. 
     
     
         11 . A sound chamber including at least one sound absorbing structure, which is constituted of a vibration member composed of a closed-cell porous material and an open-cell porous material which are laminated together, and an air cavity formed in a rear side of the closed-cell porous material. 
     
     
         12 . A sound chamber including at least one sound absorbing structure, which is constituted of a vibration member composed of a closed-cell porous material and an air-permeable member which are laminated together, and an air cavity formed in a rear side of the closed-cell porous material.