An acoustic transducer having a piezoelectric element secured to a conical diaphragm with the piezoelectric element forming part of a relaxation oscillator circuit. The piezoelectric element performs the dual function of firstly developing acoustic energy and transferring such energy to the diaphragm and secondly functioning as an electronic component in the oscillator circuit by operating as a frequency determining capacitor in such circuit. The diaphragm and the piezoelectric element are enclosed in a housing. Portions of the housing are deformed and penetrate the base of the diaphragm for securing the diaphragm to the housing. A post integral with the housing extends inwardly from the base toward the apex of the diaphragm and one end of the post is disposed adjacent the apex to prevent collapse of the diaphragm.