Back pressure operated sound transmitter

A pressure gas driven, back pressure operated sound transmitter, comprising a housing, a back pressure chamber and an inlet chamber in said housing, a diaphragm forming a partition between said back pressure chamber and said inlet chamber, a pressure gas inlet to said inlet chamber, a resonance horn connected to said housing, an inlet end of said resonance horn protruding into said inlet chamber, an annular seat on said inlet end for cooperation with said diaphragm, said diaphragm being adapted sealingly to abut said seat for disrupting gas communication between said inlet chamber and the interior of said horn and to oscillate away from said seat for establishing such gas communication, throttle passage means forming a constant communication between said inlet chamber and said back pressure chamber, an operating valve, an inlet of said operating valve being connected to said back pressure chamber, damping chamber means, an outlet of said operating valve being connected to said damping chamber means, and pressure reduction valve means connected to said damping chamber means for venting said damping chamber means to the ambient atmosphere, said damping chamber means having an interior volume being 1.5 to 3 times as large as the interior volume of said back pressure chamber so as to ensure proper start of the sound transmitter on the fundamental frequency and with the proper amplitude and maintenance of such frequency and amplitude throughout the operation of the sound transmitter.