A sound emitting device for providing at least one new sonic or subsonic
frequency as a by-product of emitting a waveform of at least two
ultrasonic frequencies whose difference in value corresponds to the
desired new sonic or subsonic frequency. The device includes a parametric
emitting perimeter or plurality of emitter segments positioned around a
central open section. This open section is structured with a diagonal
width greater than a cross-sectional diagonal of the parametric emitting
perimeter. An ultrasonic frequency signal source and sonic/subsonic
frequency generator are coupled together to a modulating circuit for
mixing an ultrasonic frequency signal with an electrical signal
corresponding to the at least one new sonic or subsonic frequency. The
modulator output is coupled to the emitting perimeter which comprises
ultrasonic frequency emitting material for propagating the mixed waveform
into air for demodulating the waveform to generate the at least one new
sonic or subsonic frequency.