A preprocessing method to increase high frequency response of a parametric loudspeaker

Unlike a conventional loudspeaker, a parametric loudspeaker whose principle is derived from nonlinear acoustic effects in air can create a controllable sound beam with a compact emitter. Therefore, the parametric loudspeaker is advantageous in deployments where personal audio zones are in demand. However, it is a dilemma that the sound generation principle of parametric loudspeaker leads to a narrow bandwidth of itself, which hinders its popularization in applications requiring high fidelity. In this paper, we propose a tentative treatment of harmonic distortions incurred in parametric loudspeakers, whereby the asymmetrical amplitude modulation (AAM) method is used to extend the high frequency response by doubling the higher cut-off frequency.