A turned double-layer microperforated panel for low frequency sound absorption in enclosures with limited cavity space

Abstract

A new type of sound absorption structure based on a double-layer microperforated panel (DLMPP) and the concept of a flip-up space in analogy to the coiled-up space is presented in this paper to improve the low-to-mid frequency sound absorption in enclosures with limited backing air cavity space. It is shown that the new design can produce a wide-band sound absorption similar to a conventional DLMPP, and the flip-up of the cavity can realize a low frequency sound absorption for enclosures with limited backing cavity space. Both theoretical analysis and finite element simulation are presented for the prediction of sound absorption coefficient of the new design. Effects of the design parameters on the sound absorption coefficient of the new design are also discussed. A particle swarm optimization (PSO) algorithm is then employed in finding the optimized parameters of the design for the optimal sound absorption performance. The predicted sound absorption results of the new design are verified in the experimental investigation using a sound impedance tube.