On the use of micro-perforated panels for sound absorption

This study deals with the sound absorption for Micro-Perforated Panels (MPP) as an effective solution for sound reduction. Single and multiple MPPs backed by an air cavity are presented, analysed, and both their behaviour and response are modelled and measured. The experimental setup relies on the use of an impedance tube. Three MPP samples were fabricated for this study: two MPP samples are made of Aluminium and one sample is polymer-made to analyse the contribution of the panel vibration to the overall sound absorption. To support the analysis, two models are presented: a model based on the acoustic propagation in short and narrow tubes and a model based on the equivalent fluid. Both models are compared to the experimental data and discussed. The theory considers no interactions between the holes. It is particularly showed that the sound absorption in the low-frequency ranges can be enhanced by using the combined effects of multiple MPPs and their vibrational effects. Relatively good agreement is also observed between the prediction and the measurement. The study suggests the present technique as a relatively easy and cheap technique for enhancing the sound absorption of systems including MPPs backed by air cavity.