Traffic noise radiation suppression in an unbaffled long enclosure using micro-perforated panel

Abstract

Sound radiation control of an unbaffled long enclosure using corrugated Z-shaped micro-perforated panel absorbers (ZMPPAs) is investigated. First, a hybrid model based on the finite element method (FEM) and the Wiener-Hopf (WH) technique is established to calculate the sound pressure level (SPL) radiated from an unbaffled long enclosure. Subsequently, an array of ZMPPAs is proposed to absorb higher-order acoustical modes inside the long enclosure so that the radiated noise can be suppressed. After that, the sound attenuation performance of ZMPPAs is evaluated and compared with that of corrugated and flat microperforated panel absorbers (CMPPAs, FMPPAs). The results demonstrate that ZMPPAs can reduce the radiated SPL within a wide frequency range which is favorable for the suppression of environmental noise. Finally, the performance of the ZMPPAs, CMPPAs, and FMPPAs in reducing the radiated noise from an unbaffled long enclosure is examined using a quasi-2D test rig. The experimental results coincide well with the calculated results which validates the proposed model and verifies part of the numerical findings.