Sonic pin detection means

Claim 1

IN COMBINATION WITH A BOWLING ALLEY, APPARATUS FOR DETECTING THE PRESENCE OR ABSENCE OF A STANDING BOWLING PIN ON THE ALLEY BY DISTINGUISHING BETWEEN A FIRST CONDITION REPRESENTED BY THE PRESENCE OF A STANDING PIN AND SECOND CONDITION REPRESENTED BY THE ABSENCE OF A STANDING PIN, COMPRISING, AN ACOUSTICAL SYSTEM INCLUDING AN ELECTROMECHANICAL TRANSDUCER ADJACENT A PIN SPOT ON THE ALLEY FOR PRODUCING SOUND WAVES, MEANS COUPLING THE TRANSDUCER TO THE MATERIAL OF THE ALLEY AT THE PIN SPOT SUCH THAT VIBRATIONS OF THE TRANSDUCER ARE TRANSMITTED TO THE PIN SPOT, SAID ACOUSTICAL SYSTEM BEING RESPONSIVE TO A BOWLING PIN AND HAVING A PREDETERMINED ACOUSTICAL IMPEDANCE WHEN ONE OF SAID CONDITIONS EXISTS AND A DIFFERENT ACOUSTICAL IMPEDANCE WHEN THE OTHER CONDITION EXISTS, AND AN ELECTRICAL SYSTEM CONNECTED FOR SUPPLYING POWER TO THE TRANSDUCER AND HAVING AN ELECTRICAL CHARACTERISTIC WHICH IS ALTERED BY THE CHANGE IN ACOUSTICAL IMPEDANCE THEREBY TO PROVIDE A SIGNAL INDICATIVE OF THE CHANGE.