Miniaturized helmet exponential horn speaker for a portable radio receiver

Claim 1

IN LIGHT PORTABLE RADIO RECEIVING APPARATUS, A TRANSDUCER FOR CONVERTING ELECTRICAL WAVES TO SOUND WAVES, A THIN SOLID FLAT MEMBER HAVING A DEPRESSION IN ONE FACE INTO WHICH SAID TRANDUCER FITS AND IS SUPPORTED, SAID MEMBER HAVING AN OPENING THERETHROUGH FROM THE BOTTOM OF THE DEPRESSION TO THE OTHER FACE THROUGH WHICH SOUND WAVES EMANATING FROM THE TRANSDUCER MAY PASS, AN EXPANDING SPIRAL GROOVE IN THE OPPOSITE FACE OF THE MEMBER HAVING ITS INCEPTION AT ONE END OF THE OPENING THROUGH THE MEMBER, SAID GROOVE BEING SO DESIGNED THAT ITS CROSSSECTIONAL AREA EXPANDS APPROXIMATELY EXPONENTIALLY AND TERMINATES AT ONE EDGE OF THE MEMBER AND A PLATE WHOSE COUNTOUR FITS THE SIDE OF THE MEMBER REMOTE FROM THE TRANSDUCER TO SEAL THE SIDE AND FORM AN APPROXIMATELY EXPONENTIAL CHANNEL, SAID PLATE BEING AFFIXED TO SAID THIN FLAT MEMBER, THE SOUND WAVES GENERATED BY THE TRNDUCER PASSING THROUGH THE OPENING IN THE MEMBER AND THENCE THROUGH THE EXPONETIAL HORN FORMED BY THE CHANNEL FOR IMPROVED ASCOUTICAL IMPEDANCE MATCH BETWEEN THE TRANSDUCER DIAPHRAGM AND THE AIR.