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The acoustic behavior of micro-perforated panels (MPP) is studiedtheoretically and experimentally at high level of pressure excitation. A modelbased on Forcheimer's regime of flow velocity in the perforations is proposed.This model is valid at relatively high Reynolds numbers and low Mach numbers.The experimental method consists in measuring the acoustical pressure at threedifferent positions in an impedance tube, the two measurement positions usuallyconsidered in an impedance tube and one measurement in the vicinity of the rearsurface of the MPP. The impedance tube is equipped with a pressure driverinstead of the usual loudspeaker and capable of delivering a high soundpressure level up to 160 dB. Several MPP specimens made out of steel andpolypropylene were tested. Measurements using random noise or sinusoidalexcitation in a frequency range between 200 and 1600 Hz were carried out onMPPs backed by air cavities. It was observed that the maximum of absorption canbe a positive or a negative function of the flow velocity in the perforations.This suggests the existence of a maximum of absorption as a function of flowvelocity. This behavior was predicted by the model and confirmedexperimentally.

On the variations of acoustic absorption peak with flow velocity in Micro-Perforated Panels at high level of excitation