Estimation of acoustic properties for porous material with surface acoustic impednace

Abstract

In this study, estimation of acoustic properties of porous material with surface acoustic impedance was proposed and compared with other methods. To estimate complex characteristic impedance and wavenumber of porous material, four microphone impedance tube or two-thickness method were widely used. In the two-thickness method, complex propagation constant and characteristic impedance was calculated with measured surface acoustic impedances. Through the proposed method, porous material's wavenumber and characteristic impedance is calculated with small different thicknesses of samples. Surface acoustic impedance was measured by two microphone impedance tube method to estimate complex wavenumber, and comparison of acoustical properties estimated through proposed method was performed. Non-acoustical properties of porous materials were also calculated through indirect method. The results showed good estimation compared with other measurement method.