Unidirectional microphone

Claim 1

A PRESSURE GRADIENT MICROPHONE HAVING DIRECTIONAL PROPERTIES WITHIN A FREQUENCY BAND COMPRISING A HOUSING HAVING A SOUND PORT THEREIN, AN ELECTROACOUSTICAL TRANSDUCER HAVING A DIAPHRAGM CONFRONTING THE SOUND PORT ON ONE SIDE, SAID HOUSING HAVING FIRST AND SECOND OPENINGS, THE FIRST OPENING BEING SPACED FROM THE SOUND PORT BY A SHORTER DISTANCE THAN THE SECOND OPENING, SAID HOUSING HAVING MEANS DEFINING A FIRST SOUND PATH BETWEEN THE FIRST OPENING AND THE SIDE OF THE DIAPHRAGM OPPOSITE THE SOUND PORT AND A SECOND SOUND PATH BETWEEN THE SECOND OPENING AND SAID SIDE OF THE DIAPHRAGM, SAID MEANS INCLUDING A CHAMBER COMMON TO BOTH SOUND PATHS AND IN COMMUNICATION WITH THE DIAPHRAGM, AN ACOUSTICAL IMPEDANCE OPERATIVELY ASSOCIATED WITH THE FIRST SOUND PATH, MEANS OPERATIVELY ASSOCIATED WITH THE SECOND SOUND PATH FOR LIMITING THE FREQUENCIES TRANSMITTED THERETHROUGH TO A LOW FREQUENCY BAND, THE FIRST SOUND PATH TRANSMITTING A SECOND BAND OF FREQUENCIES ABOVE THE LOW FREQUENCY BAND AND INCLUDING THE HIGHER FREQUENCIES OF THE LOW FREQUENCY BAND, THE LENGTH OF THE FIRST SOUND PATH SHIFTING THE PHASE OF SOUND WAVES ABOVE THE LOW FREQUENCY BAND APPROXIMATELY THE SAME AS THE LENGTH OF THE SECOND SOUND PATH SHIFTS THE PHASE OF SOUND WAVES WITHIN THE LOW FREQUENCY BAND, SOUND WAVES OF A FREQUENCY WITHIN BOTH THE LOW AND HIGH FREQUENCY BANDS BEING TRANSMITTED TO THE DIAPHRAGM THROUGH BOTH THE FIRST AND THE SECOND SOUND PATHS.