Electret microphone

A capacitor transducer comprising, in combination, an electrically conducting housing having an opening at one end for the passage of sound waves, a vibratile electrically conducting diaphragm mounted within the housing confronting the opening and electrically connected to the housing, an electrically conducting plate mounted within the housing on the side of the diaphragm opposite the opening and electrically insulated from the housing, said plate having a flat surface disposed parallel to and spaced from the diaphragm, the perimeter of said plate being acoustically sealed on the housing, and said plate having a plurality of channels extending therethrough to permit sound waves to pass through the plate, an acoustic damping member disposed within the housing and abutting the surface of the plate opposite the diaphragm, said member being constructed of electrically conducting porous material and being electrically insulated from the housing, a support member of electrically insulating material disposed within the housing confronting the acoustic damping member on the side thereof opposite the electrically conducting plate, electrical contact means mounted on the support member and abutting the acoustic damping member including an electrically conducting pin and a spring mounted on the pin for maintaining pressure between the pin and the damping member.