Sensitivity analysis of micro-perforated panel absorber models at high sound pressure levels

Abstract

Sensitivity analysis is performed using a nonlinear acoustic impedance model of micro-perforated panel absorbers constituted by a micro-perforated panel bonded on a honeycomb structure in order to assess the impacts of the input parameters on the outputs of interest namely the normalized surface impedance and the sound absorption coefficient. The theoretical results predicted by the nonlinear impedance model show good agreement with experimental measurements performed at high sound pressure level using an impedance tube. The inputs of the model are the plate thickness, the orifice diameter, the perforation ratio, the cavity depth and the sound pressure level. For higher pressure levels excitations, it is demonstrated that the perforation ratio is the key parameter which affects significantly the resistance and the sound absorption of the absorber at the resonance while the impacts of the thickness and orifice diameter of the panel are negligible. In addition, the study confirms that the acoustic reactance is dominated by the cavity depth especially at low frequencies and the sound pressure level influences strongly the acoustic behaviour of micro-perforated panel absorbers. Therefore, the design of a micro-perforated panel absorber requires the knowledge of the sound pressure level and the perforation ratio control quality must be done carefully in order to get the target performances of the absorber.