Nonlinear Sound Attenuation Analysis of Micro-Perforated Panel Absorbers Under Higher Sound Pressure Excitations

In this paper, the nonlinear sound attenuation performance of a single, double, and triple-layer microperforated panel (MPP) absorbers is studied at high sound pressure level (SPL). Experimental measurements are performed using a high SPL impedance tube capable of delivering noise levels up to 155 dB. The theoretical sound absorption coefficient using an equivalent fluid impedance model, which is a function of the incident pressure, shows good agreement with the measurements. For a single layer MPP absorber, it is observed that the acoustic resistance increases as well as the absorption resonant peak and the frequency band as the SPL increases. For a double and triple-layer MPP absorbers, the sound absorption coefficient exhibits, respectively, two and three resonant peaks that are significantly impacted by the SPL that affects the reactance of multilayer system while for a single layer absorber the reactance is slightly influenced. For a double layer MPP absorber, the effects of the perforation ratios and the internal MPP position are illustrated. A single, double, or triplelayer MPP absorbers that may present poor sound absorption in the linear regime can become effective at high SPL. Therefore, the SPL is an important parameter that must be considered in the design of single, double, and triple-layer MPP absorbers.