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CARDIOID MICROPHONE

  • US 3,585,317 A
  • Filed: 01/04/1968
  • Issued: 06/15/1971
  • Est. Priority Date: 01/04/1968
  • Status: Expired due to Term
First Claim
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1. A directional microphone of the cardioid type, having one side of its diaphragm exposed directly to sound waves in air, and having the other side of the diaphragm closed off from direct contact with said sound waves by an acoustic delay path leading partly through A controlled distance in porous material and partly through an open slot at an edge of said porous material, said delay path being divided into parallel courses and said porous material and said slot are both made plural so that at least one portion of said material and one of said slots exist in each of said parallel courses, the portions of porous material in said parallel courses being of different density.

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