Narrow-edged Beamforming Using Masked Parametric Array Loudspeakers

Parametric array loudspeakers (PALs) can achieve superior directivity by using the straightness of ultrasonic waves. However, the demodulated sound beam in small-scale PALs has a tendency to spread easily. In this study, we propose a beamforming method for small-scale PALs using masked PALs. Specifically, the whole parametric array is divided into a main array on the interior and a split sub-array, with half of the sub-array on each side of the main array. A normal modulated wave is emitted from the main array, while a phase-inverse modulated wave is emitted from the sub-array. The parametric effect is masked spatially to increase the narrowness of the demodulated sound beam. Finally, we experimentally demonstrated the effectiveness of the proposed method.