Multi-Beam Design Method for a Steerable Parametric Array Loudspeaker

The parametric array loudspeaker (PAL) uses an ul-trasonic transducer array (UTA) to transmit inaudible ultrasonic frequencies into air, in order for an audible difference frequency to be produced by the parametric acoustic array (PAA). The PAL is advantageous as it possesses a much narrower sound beam as compared to the conventional loudspeaker of the same size. The mixed Gaussian directivity method has been previously proposed in a single-beam design method of the PAL to approximate the Westervelt's directivity. It allows the convolution model to be analytically decomposed into solvable equations. Due to the nonlinear nature of the PAL, linear combinations of singlebeam designs do not readily yield a multi-beam design. For this reason, this paper establishes a specific multi-beam design method and validates its effectiveness by 2D nonlinear acoustic field simulations.