Prediction of microperforated panel absorbers using the finite-difference time-domain method

Abstract

Microperforated panel (MPP) sound absorbers give selective but relatively wide and high sound absorption. In addition, they are environmentally friendly, hygienic, and visually attractive. As such, MPPs are very promising alternatives for next-generation sound absorbers. The effects of MPPs have been predicted by analytical approaches as well as numerical techniques such as the finite element method, the boundary element method, and computational fluid dynamics. However, the effects have yet to be predicted by the finite-difference time-domain (FDTD) method. In this paper, the FDTD formulation is proposed as an option to predict the acoustic performance of MPPs. For the time-domain calculations, the frequency dependence of the transfer impedance for a hole in an MPP is approximated based on regression analyses, which removes the frequency dependence. Furthermore, the stability conditions for the MPP boundary are derived by considering the state transition equations. Comparisons of numerical and analytical results verify the formulation.