Investigation of the acoustic properties of corrugated micro-perforated panel backed by a rigid wall

Abstract

Extensive studies have been carried out on the acoustic performance of a micro-perforated panel (MPP) absorber which typically consists of a flat MPP fitted in front of a rigid backing wall. The present study concerns its acoustic properties when the conventionally flat perforated panel is replaced with a corrugated one that finds many applications in architecture. A three-dimensional finite element model is used to simulate the acoustic performance of a such corrugated MPP absorber at normal incidence, oblique incidence and diffuse field. Results show that the absorption performance of corrugated MPPA can be very different from conventional flat MPPA when the acoustic wave length is smaller than the corrugation depth. At low frequencies, the corrugated MPP performs similarly as a flat one of the same bulk perforation ratio. The absorption levels of the corrugated MPPA are considerably enhanced at the dips of absorption curves, which is favorable for reverberation control or broadband random noise reduction in large spaces and buildings. Further modal analysis shows that multiple modes of the corrugated configuration are excited at the peak and dip frequencies, and the acoustic response by the non-resonating modes give rise to the performance improvement. Absorption coefficients are also measured experimentally using an impedance tube. The measured normal incidence absorption coefficients compare well with the numerical predictions, which validates the numerical model and, in part, the numerical findings.