Experimental assessment of the sound absorption coefficient of three natural fibers

Abstract

The acoustic absorptive materials used in noise control stand out for the high efficiency in sound absorption. However, many of these materials are synthetic and hence they have a long or indeterminate decomposition time and does not allow their disposal in nature. In addition, if these materials suffer other destination as incineration in industrial furnaces, they may release toxic gases harmful to health and the environment. Natural fibers are an alternative for the replacement of synthetic materials used in acoustic insulation or in the reverberating surfaces treatment. The main objective of this work is to assess the acoustic efficiency of sisal, coconut husk and sugarcane bagasse fibers in terms of their sound absorption coefficient. The samples were experimentally assessed with the 100 mm diameter impedance tube according to the ASTM C1050-12 standard. The samples evaluated have 30, 40, and 50 mm thick and were tested with and without air gap between the samples and the back rigid of the tube in low and medium frequencies. Moreover, perforated plates were introduced in front of the samples to increase their efficiencies.