Analysis on sound absorption of natural coir fiber using Delany-Bazley model

Abstract

This paper explores the sound absorption capacity of natural coir fiber. Absorption coefficient of coir fiber is calculated using Delany-Bazley model. Experiments are conducted in impedance tube to validate the analytical outcomes for three samples having different thickness. Increasing the thickness of coir fiber enhances sound absorption and shifts noise absorption peak towards low frequency. Moreover, effect of air gap on sound absorption performance of coir fiber has also been investigated. Increasing air gap thickness usually shifts the peak of absorption coefficient towards lower frequency. Then, the noise absorption of coir fibers with and without air gap is compared and shows that earlier one has greater absorption at low frequency than the later one. However, resonances can not be predicted using this technique. Results also indicate that Delany-Bazley equations can justify the overall trend of absorption coefficient of coir fiber perfectly as demonstrated in this study.