Analysis of a parametric speaker by using concentrated mass model

Abstract

Parametric speakers can output beam-shape audible sound by using the non-linear interaction of ultrasonic waves. In recent years, a sound absorption coefficient measurement method using a parametric speaker has been proposed, and parametric speakers are increasingly being used in acoustic spaces with reflective. Many discrete analyses by using finite difference time domain method have been proposed as analysis methods for parametric speakers, but the methods have problem that the calculation load is heavy. In this research, we construct a steady-state response analysis method that can efficiently analyze the audible sound of parametric speakers. We propose a method that combines a nonlinear concentrated mass model and a perturbation method. Impedance boundaries are set at the edges of the acoustic space to accommodate reflective spaces. In this report, we create an axisymmetric two-dimensional model and confirm the validity of the proposed model by numerical calculation in the acoustic space without reflection at the boundaries.