Density Influence on Acoustic Performance of Waste Composite Materials

This study aimed to determine the effect of material density on the sound absorption coefficient (SAC) of composite materials made from rice husk, rice straw, and sawdust. Rice husk, rice straw, and sawdust were made into composite materials with volume fraction variations of 30:70, 25:75, and 20:80 with a thickness of 25 mm. The samples were tested in the 200–1600 Hz frequency range using two microphones and a type 4206 impedance tube in accordance with ASTM E1050 standards. The test findings showed that the composite material made of rice straw had the best SAC at 1600 Hz with an ? value of 0.72 and a volume fraction variation of 30:70, probably because it was less dense than the other materials. The maximum SAC values for the 30:70 volume fraction variation were 0.72 for the rice straw composite material at 1600 Hz, 0.42 for the rice husk composite material at the same frequency, and 0.13 for the sawdust material at 1000 I Hz. The discussion leads one to believe that the SAC is heavily influenced by the bulk density of the forming fiber material and the density that is generated by the fluctuation in volume fraction of a composite material.