Abstract: A system using the nonlinearity of a propagation medium to demodulate an ultrasonic wave having audio modulated onto the ultrasonic frequency, audio signal processing circuitry providing a delayed audio signal and an envelope signal which is a function of peaks of the audio signal over a predetermined interval. The delayed audio signal and the envelope signals are combined with the delay in the audio allowing the envelope signal to accurately be aligned with the audio signal in the combination.

Abstract: An ultrasonic transducer having a reduced cost of manufacture. The ultrasonic transducer includes a first insulative retaining layer, a second insulative retaining layer, and a vibrator film layer sandwiched between the first and second retaining layers. The first retaining layer includes a first plurality of apertures formed therethrough, and the second retaining layer includes a second plurality of apertures formed therethrough, in which the second apertures are substantially in registration with the first apertures. The ultrasonic transducer further includes a first cover portion having a plurality of spring/backplate assemblies connected thereto, and a second cover portion. The combination of the first retaining layer, the vibrator film layer, and the second retaining layer is sandwiched between the first and second cover portions of the ultrasonic transducer.