Effect of geometrical parameters of elliptically perforated plates on the sound absorption performance

The integration of perforated plates in acoustic applications has gained interest for their effectiveness in noise mitigation, especially in low to mid-frequency ranges, while keeping a lightweight and compact design. However, significant absorption at lower frequencies remains challenging, as performance is closely tied to pore geometry. This study investigates the effect of geometric parameters, namely, the eccentricity of elliptical pores and pore area, on sound absorption performance in two configurations: one with an airgap backing layer and the other with melamine foam. The plates were fabricated using stereolithography 3D printing, and sound absorption testing was conducted between 200-4300 Hz via impedance tube tests, following ISO standard 10534-2. Results indicate that increased eccentricity enhances absorption rates at mid to high frequencies, particularly in micro-perforated plates (equivalent diameter < 1mm). The inclusion of the melamine foam layer significantly boosts absorption in the mid-low frequency range. In conclusion, modest eccentricity and pore area changes can substantially improve sound absorption, indicating potential for future research on optimal configurations to maximize performance in lower frequency ranges.