Performance of Natural Multi-layer Coir and Kenaf Fibers as Sustainable Acoustic Absorber

Abstract Research on natural materials as alternative sound absorbers for buildings continues. This paper presents a natural sound absorber composed of multi-layer coir and kenaf fibers. Normal and random incidence sound absorption measurements were conducted to evaluate the sound absorption performance. The results indicate that adding a thin kenaf fiber layer significantly enhances the sound absorption of the coir fiber. This improvement is observed in the low to mid-frequency range when the kenaf layer, with a smaller thickness than the coir fiber layer, is positioned at the outermost layer. If the kenaf layer is adjacent to a rigid surface, the improvement is predominantly in the mid to high-frequency range. However, if the thickness of the kenaf layer exceeds that of the coir layer, the experiment and Miki’s model demonstrate that the sound absorption coefficient remains nearly identical at mid to high frequency regardless of the arrangement of the layers.