Effect of porosity on the use of multiple perforated plates with coir fiber acoustic absorber

Abstract

The objective of this work is to explore and analyze the effect of porosity on the use of mul-tiple perforated plate (hereafter PP) implemented with coir fiber acoustic absorber. Previous-ly developed analytical method for multilayer PP absorber employing Allard and Sgard mod-el together with acoustic transmission approach and Johnson-Allard rigid frame model was utilized to estimate the absorption coefficient of the absorber in different conditions. The ve-rification of the estimated acoustical absorption coefficient for multiple PP absorber using the developed method are shown for two different combination compromises of two PP, coir fi-ber and or air gap. Measurements were conducted in impedance tube on normal incidence sound absorption of the panel. It shows that the presented analytical method can provide a fa-vorable and consistent agreement with the experimental results. Therefore, it was anticipated that this analytical approach can be used efficiently for exploring and analyzing the factor that may significantly contributes and control the absorption behavior of multiple PP absor-ber in the use of coir fiber. In this research, only two layer PP absorbers are analyzed to de-scribe the characteristic factors as a preliminary study for multiple PP absorbers. The acoustic features of the multiple PP acoustic absorbers such as effect of PP porosity with the variation of arrangement of PPs and backing compartment employed with PP are discussed in details. Those elements seem to have a significant contribution on the absorption characteristics of the absorber. In addition, it was noticed that porosities of PP can be engineered based on per-formance of the panel and designed for developing an effective coir fiber absorber utilizing multiple PP in future. Moreover, some recommendations were made based on the results of the analysis. Furthermore, these result presented here encourage more awareness during the real application of coir fiber in acoustics with multiple PP system.