Mathematical and experimental investigation of sound absorption behavior of sustainable kenaf fiber at low frequency

Abstract

Natural materials are being employed as an option for controlling noise pollution, mainly via sound absorption mechanism. Specifically, natural fibers have been selected for use since they are environmentally friendly as well as easily and abundantly available. This paper discusses the mathematical and experimental examination of the sound absorption behavior of sustainable kenaf fiber at low-frequency range using the Delany–Bazley model (D–B model) as well as Nelder–Mead method and comparing the results with experimental findings. For this reason, we prepared S1-S16 samples of natural kenaf fibers at different thicknesses and bulk densities to measure the values of airflow resistivity and sound absorption coefficients. The predicted values obtained from both the D–B model and best-fit inverse approach presented by the Nelder–Mead method compared with experimental data measured using impedance tube. Accordingly, by applying a least-square fit procedure, the values that have best predicted both the impedance test and the propagation constant laws were evaluated. The inverse laws approach applied to determine the different physical parameters such as porosity, thickness, airflow resistivity as well as predicting the absorption performance of the kenaf fiber at low frequency ranges.