Acoustic attenuator and method of attenuation of noise

Abstract

A sound reducer or sound attenuator for use in cabinets and the like with the sound reducer comprising a plurality of small bead like acoustic resonators loosely held in position between two members with each of the acoustic resonators having an acoustical resonance cavity therein for generating a standing wave with the standing wave producing vibration displacement of the acoustic resonators thereby dissipating acoustical sound energy through mechanical work.

We claim:  
     
         1 . A liner for reducing internal acoustic noise comprising: 
 a sound penetrable member;    a second member, said second member spaced from said first member and cooperating with said sound penetrable member to form a hollow there between;    a plurality of acoustic resonators positioned between said sound penetrable member and said second member, each of said plurality of acoustic resonators having an opening and an acoustical resonance cavity therein for ingress of a sound wave whereby the acoustical resonance cavity generates a resonance sound wave causing vibration displacement of each of said plurality of acoustic resonators thereby causing dissipation of the sound wave by conversion of acoustical energy into vibration energy.    
     
     
         2 . The liner of  claim 1  wherein the plurality of acoustic resonators includes acoustic resonators of different mass.  
     
     
         3 . The liner of  claim 1  wherein the plurality of acoustic resonators includes acoustic resonators of different length cavities.  
     
     
         4 . The liner of  claim 3  wherein the plurality of acoustic resonators includes acoustic resonators of different mass.  
     
     
         5 . The liner of  claim 1  wherein the first penetrable sound member comprises a mesh screen.  
     
     
         6 . The liner of  claim 1  wherein the acoustic resonators comprises ceramic beads.  
     
     
         7 . The liner of  claim 1  wherein the acoustic resonators comprises glass beads.  
     
     
         8 . The liner of  claim 1  wherein the liner comprises a portion of a cabinet.  
     
     
         9 . The liner of  claim 1  wherein the liner comprises an integral portion of a cabinet.  
     
     
         10 . The method of attenuation the noise within a cabinet comprising: 
 placing a sound penetrable member within the cabinet;    placing a second member in a spaced condition from the sound penetrable member to create a space there between; and    placing a plurality of acoustic resonators in the space so that noise generated within the cabinet that impinges on the acoustic resonators is attenuated by translation of acoustical energy into vibration energy that displaces each of the plurality of acoustic resonators.    
     
     
         11 . The method of  claim 10  wherein the step of placing a plurality of acoustic resonators in the space comprises placing acoustic resonators having cavities of different lengths therein.  
     
     
         12 . The method of  claim 11  wherein the step of placing a plurality of acoustic resonators in the space comprises placing acoustic resonators of different external sizes in the space.  
     
     
         13 . The method of  claim 12  wherein the step of placing a plurality of acoustic resonators in the space comprises placing acoustic resonators of different materials in the space.  
     
     
         14 . The method of  claim 13  wherein the step of placing a plurality of acoustic resonators in the space comprises placing acoustic resonators of different mass in the space.  
     
     
         15 . The method of  claim 14  wherein the step of placing a plurality of acoustic resonators in the space comprises placing a sound penetrating mesh on a side of the liner exposed to acoustical wave energy.  
     
     
         16 . A liner for reducing internal acoustic noise comprising: 
 a sound penetrable member;    a second member, said second member spaced from said first member and cooperating with said sound penetrable member to form a hollow there between; a plurality of acoustic resonators positioned between said sound penetrable member and said second member, each of said plurality of acoustic resonators spaced from an adjacent acoustic resonator therein to provide a labyrinth pathway for passage of a sound wave from said sound penetrable member to said second member thereby causing attenuation of the sound wave as the sound wave propagates through the labyrinth pathway.