The acoustic properties of airlaid nonwoven panels made of Posidonia and Alfa natural fibers are compared to Hemp fibers. The acoustic performance of the panels is studied as a function of density and thickness. Experimental and modeling approaches are both considered. First, porosity and airflow resistivity are determined experimentally for several densities and compared with extrapolated values. This allows predicting the acoustic equivalent fluid properties for any density. Impedance tube measurements are then performed to determine the acoustical absorption coefficient. The equivalent fluid model, together with the extrapolated porosity and airflow resistivity for a given panel density, provides a good comparison with the measurements. The sound absorption properties of 0.04 and 0.08 m thick panels for densities of 40 and 80 kg/m3 is finally compared for the three materials. We show that natural Posidonia and Alfa fibers have comparable efficiencies to Hemp fibers and can contribute to the development of more sustainable sound absorption materials.
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