Audible sound analysis of parametric speaker by concentrated mass model (Steady-state response analysis for cylindrical acoustic space by substructure synthesis method)

Parametric speaker can radiate an audible sound beam with sharp directivity by using the nonlinear interaction of ultrasonic waves. In recent years, the highly directional audible sound generated by the parametric speaker has been applied to various applications. For example, applications such as active noise control, sound absorption coefficient measurement, and creation of audio spots have been proposed. Numerical analysis of nonlinear sound field is important in application design. Many discrete analyses by using finite difference time domain method have been proposed as analysis methods for parametric speakers, but these methods have problem that the calculation load is heavy. Therefore, there is a need for efficient analysis methods for parametric speakers. In this study, we construct a steady-state response analysis method that can efficiently analyze the audible sound of parametric speakers. The method is combined a nonlinear concentrated mass model and a perturbation method. In addition, the computational load of the constructed model can be reduced by combining the substructure synthesis method. The proposed method is suitable for analysis of parametric speakers because the number of divisions in the axial direction can be set very large. The validity is confirmed by comparing the analysis result of the proposed method with the solution of the KZK equation. In addition, the improvement in calculation efficiency by the substructure synthesis method has been confirmed by numerical calculation.