Although the mechanisms involved remain unclear, several studies have reported that bone-conducted ultrasounds (BCUs) can be perceived even by those with profound sensorineural hearing impaired, who typically hardly sense sounds even with conventional hearing aids. We have identified both the psychological characteristics and the neurophysiological mechanisms underlying the perception of BCUs using psychophysical, electrophysiological, vibration measurements and computer simulations, and applied to a novel hearing aid for the profoundly hearing impaired. Also, mechanisms of perception and propagation of the BCU presented to distant parts of the body (neck, trunk, upper limb) were investigated.