Pole identification method to extract the equivalent fluid characteristics of general sound-absorbing materials

A method is presented to characterize general sound-absorbing materials through a pole-based identification of the equivalent fluid. This accomplished by 1) determining extended fluid material sample transfer function (TFM), 2) acoustic response poles effective density and compressibility, 3) build compressibility from associated local response. Real pole pairs describe dissipative medium (or equivalently an over-damped resonating medium), which natural behavior rigid-frame porous materials, while complex-conjugate locally-resonant typical metamaterials. Complex-conjugate elastic resonances are discarded. We test for several non-conventional materials. In general, better fit measured surface impedance obtained than with acoustics-based Johnson-Champoux-Allard-Pride-Lafarge model (JCAPL), appears also be robust errors TFM.