A parametric array loudspeaker (PAL) is a highly directional sound source with a small aperture size. To achieve accurate sound projection, the technology of beam steering for PAL is necessitated. The steerable PAL is implemented by the phased array technology. In this paper, a practical steerable PAL sound field model based on the Westervelt equation is established, and a quasi-linear approximation is used to obtain the spatial sound pressure distribution. By applying the phased array technology, the audio beam can steer to the target direction. However, the grating lobe arises when the transducers are spaced more than half a wavelength, which disturbs the performance of beam steering. We further propose a grating lobe suppression method called phase-randomization array (PRA) and apply it to the steerable PAL. Simulations validate that the grating lobe of the steerable PAL is suppressed.

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