Modified theory of a microperforated panel with roughened perforations

Microperforated panels (MPPs) play important roles in sound absorbing systems. The classical Maa theory for the MPPs is modified to account for the effect of roughness on the surface of microperforations on sound absorption. Correspondingly, the relative acoustic resistance and relative acoustic mass of the system are determined theoretically. Full numerical simulations with the method of finite elements are performed on the roughened MPP to validate the modified theory, with good agreement achieved. It is demonstrated that surface roughness decreases resonant frequency and promotes viscous dissipation, thus enhancing the sound absorbing capability of the MPP. This work extendes Maa's theory for the sound absorption of MPP from smooth perforations to rough perforations. The modified theory for MPP with roughened perforations has a great significance in sound absorption field, since it is more applicable for the realistic situations