An acoustic impedance structure consisting of perforated panel resonator and porous material for low-to-mid frequency sound absorption

In this paper, an acoustic impedance compound structure composed of a perforated panel resonator (PPR) and porous sound absorbing material (PSAM) is designed to improve the sound absorption for low-to-mid frequency. The PPR component is an array cell of multiple Helmholtz resonators based on perforated panel arranged in parallel. By properly introducing a PSAM component that consists of porous material layers and rigid wall into the PPR component, a matched acoustic impedance appears at the coupling of the PPR and PSAM. Thus, the designed composite structure PPR-PSAM achieves an effective wide-band sound absorption through the effect of resonance dissipation by PPR and trapped energy by PSAM. An analytical model based on acoustic-electrical analogy is established to predict the sound absorption, and a finite element model is further proposed to demonstrate the sound absorption mechanism for the PPR-PSAM. Moreover, the influences of structural parameters on the sound absorption of the PPR-PSAM are discussed, and the sound absorption of the PPR-PSAM and the MPP (microperforated plate), MPP-PSAM are compared. The normal sound absorption coefficient measured by impedance tube is well agreed with the predicted results. In a limited space of 80 mm, the PPR-PSAM with low perforation rate has an average sound absorption coefficient of more than 0.89 from 200-1600 Hz. (C) 2021 Elsevier Ltd. All rights reserved.

Automated summary

An acoustic impedance compound structure composed of perforated panel resonator (PPR) and porous sound absorbing material (PSAM) is designed to enhance sound absorption for low-to-mid frequencies. By introducing a porous sound absorbing material component into the PPR component, a matched acoustic impedance is achieved, resulting in effective wide-band sound absorption. Experimental results show that the designed composite structure PPR-PSAM has an average sound absorption coefficient of more than 0.89 in the frequency range of 200-1600 Hz.