Generation of audible sound with ultrasonic signals through the human body

This paper presents an innovative hearing system. The hearing system generates audible sound in the ears without any receivers, and no one can hear the generated sound except the user. The theory for generating audible sound is based on a self-demodulation effect which arises from the nonlinearity of the transmission medium. The nonlinear acoustics of the human body allow ultrasonic waves to interact in the transmission medium. When two ultrasonic waves with different frequencies are transmitted through the human body, an audio signal at the difference frequency of two waves is produced in the ears due to the self-demodulation effect.