Preprocessing techniques for parametric loudspeakers

Non-linear interaction of ultrasound waves can be applied to reproduce audible sound with parametric loudspeaker. This can be explained with the self- demodulation property of finite amplitude ultrasonic waves. A special characteristic of the reproduced sound waves using parametric loudspeaker is its high directivity. However, the distortion of the demodulated signal is highly dependent on the preprocessing techniques used. From our simulation results, we have shown that the distortion of the demodulated signal is significantly reduced with an orthogonal carrier.