The present invention is directed to a communication system wherein bone
conducted ultrasonic signals are used as carriers to efficiently produce
high fidelity, wide audio bandwidth sound. Exemplary embodiments rely on
the use of modulation techniques which can achieve high fidelity audible
sound, such as carrier plus single sideband (SSB) modulation. Known
non-linearities within the ear itself can be exploited to demodulate the
modulated ultrasonic carrier without producing audible sounds at the input
to the user's ear. The non-linearities of the ear itself, in conjunction
with the human brain's perception of audible frequencies generated in
response to modulated ultrasonic stimulation, are relied upon to detect
audio information.