Condenser microphone

Claim 1

A CONDENSER MICROPHONE, COMPRISING, IN COMBINATION, A HOUSING STRUCTURE; A CONDENSER ELECTRODE INCLUDING AN AT LEAST PARTLY CONDUCTIVE MEMBRANE MOUNTED IN SAID HOUSING STRUCTURE AND HAVING A FRONT FACE FACING THE FRONT SIDE THEREOF; A COUNTER ELECTRODE MOUNTED IN SAID HOUSING STRUCTURE AT A PREDETERMINED SPACING FROM THE REAR FACE OF SAID MEMBRANE; MEANS FOR INSULATING SAID ELECTRODES FROM EACH OTHER; MEANS FOR CONFINING A PREDETERMINED VOLUME OF AIR AT THE REAR SIDE OF SAID MEMBRANE WITHIN SAID HOUSING STRUCTURE; FIRST AIR PASSAGE MEANS FOR ESTABLISHING A RESTRICTED CONNECTION BETWEEN SAID VOLUME OF AIR AND THE OUTSIDE AIR AT THE REAR OF SAID HOUSING STRUCTURE; SECOND AIR PASSAGE MEANS FOR FREELY CONNECTING SAID VOLUME OF AIR AND SAID OUTSIDE AIR WITH EACH OTHER; AND MECHANICAL ADJUSTMENT MEANS FOR VARYING THE DIRECTIONAL CHARACTERISTIC OF THE MICROPHONE AND INCLUDING MOVABLE CONTROL MEANS WHICH IN A FIRST POSITION RENDER SAID SECOND AIR PASSAGE MEANS INOPERATIVE AND LEAVE SAID FIRST AIR PASSAGE MEANS OPERATIVE ONLY TO A PREDETERMINED DEGREE SO THAT THE MICROPHONE OBTAINS A DIRECTIONAL CHARACTERISTIC DEPENDING UPON SAID DEGREE OF OPERATIVENESS OF SAID FIRST AIR PASSAGE MEANS AND WHICH IN A SECOND POSITION RENDER SAID SECOND AIR PASSAGE MEANS OPERATIVE SO THAT IRRESPECTIVE OF THE OPERATIVE CONDITION OF SAID FIRST AIR PASSAGE MEANS A BI-DIRECTIONAL 8-SHAPE CHARACTERISTIC OF THE MICROPHONE IS ESTABLISHED BY THE FRICTION-FREE CONNECTION BETWEEN SAID VOLUME OF AIR AND SAID OUTSIDE AIR.