Beam Steering of Portable Parametric Array Loudspeaker

Portable devices such as smartphones and tablet PCs have become increasingly sophisticated and explosively spread. Opportunities for outdoor use have been consequently increasing. When the portable devices are used in public areas, personal audio system is required to avoid sound spread in the vicinity. We have already proposed the portable parametric array loudspeaker which can realize personal audio without using earphones and headphones. In this system, parametric array loudspeakers are mounted on two edges of tablet PCs and can radiate highly directional stereo sound to the user. However, the radiated sound beams may not focus on the user's ears when the user's head is moving. In this paper, we examine the phased array technique to steer the sound beam based on the user's head position. We demonstrate that the sound beam angle can be appropriately steered by using the phased array technique through experimental results.