Study on inhomogeneous perforation thick micro-perforated panel sound absorbers

Abstract

Micro-perforated panel (MPP) sound absorbers are usually made of a thin panel and have narrow absorption bandwidth. This drawback causes the application of MPP to be limited. In this paper, the possibility of realizing wider absorption bandwidth MPP with sufficient structural strength is investigated. For this, multi-MPP (resonator) arranged in parallel to form an inhomogeneous perforation MPP is introduced to widen the absorption bandwidth. The thickness of MPP must be 1.5 times higher than perforation diameter or more in order to have appropriate strength. The characteristics of corresponding absorption coefficients are studied parametrically using theoretical models as thick panels can reduce the MPP's performance. It is found that the absorption bandwidth of thicker panels with inhomogeneous perforation approach can be at least twice times of classical MPP. The problem of reduced peak absorption coefficient in a thick panel can be avoided by keeping the acoustic resistance value around 1± 0.5 Rayls. Compared with homogeneous MPP, inter-resonator interaction exists in the inhomogeneous perforation thick MPP that causes the overall absorption to become higher due to the increasing of the acoustic resistance as well as the shifting of peak resonance following residual acoustic reactance. The measurement results confirm all of the characteristics.

Effect of Perforation Volume on Acoustic Absorption of the 3D Printed Micro-Perforated Panels made of Polylactic Acid reinforced with Wood Fibers

“…Also, acoustic waves find it harder to enter the structure in the thicker panels, causing a decrease in SAC. Smaller acoustic reactance and higher acoustic resistance are required for an MPP to have a wider peak [20]. Increasing the perforation volume allows acoustic waves to pass through the perforations, lowering acoustic resistance and increasing reactance.…”

A tunable acoustic absorber using reconfigurable dielectric elastomer actuated petals

“…where, As the open ratio (V) is increased, like any MPP or combination of MPPs [66][67][68] , it reduces the acoustic reactance of the system following Eqs. 5 and 7.…”

Bandwidth widening for sound absorption of a flexible microperforated panel backed by a multi-frequency panel-type resonator

“…Researchers have therefore tried to widen the absorption bandwidth by using multiple layers of MPP arranged in series (Bucciarelli et al, 2019;Sakagami et al, 2006;Yang et al, 2019). They have also proposed more compact configuration by arranging different MPPs in parallel (Mosa et al, 2019(Mosa et al, , 2020Prasetiyo et al, 2016;Qian and Zhang, 2022) and also using turned double layer MPP (Zhao and Lin, 2022). Previous studies have tried to modify the backing air cavity into L-shaped cavities (Gai et al, 2017); coiled cavities (Prasetiyo et al, 2021;Wu et al, 2022); subcavities with different dimensions arranged in parallel (Guo and Min, 2015).…”