Cédric Maury, Teresa Bravo
Exposition on Noise Control Engineering
Del 25 al 29 de agosto de 2024, Nantes, Francia.
Multi-layered wall-treatments with thin lightweight micro-perforated panels offer a potential solution to achieve broadband noise absorption while complying with mass saving and compactness. This study examines how vibrational effects, often neglected, may impede the wideband acoustical performance of such partitions, made up of a distribution of either periodic or graded micro-perforated membranes or panels. The impedance translation method and a scattering matrix analysis have been implemented. It is found that the elasticity behavior of thin micro-perforated membranes has a beneficial effect on the acoustical efficiency of the partitions. The contributions of the individual acoustical resonances tend to merge if the elasticity effects are accounted for. If the partition is optimized, near-constant high absorption and low transmission values are obtained over a wide frequency range. A more robust design involves partitions made up of micro-perforated panels. It was observed that the first volumetric mode of the panels degrades the absorption properties of the partition. It crosscouples with the acoustical resonances and redistributes their spectral locations. This structural resonance sets a lower frequency bound, above which the partition can achieve a high broadband performance. It should be accounted for when setting the frequency limits of the total dissipation to be optimized.
