Prediction and measurement of acoustical property for natural fiber reinforced composite laminates

Owing to the advantages of low density, low cost, easy availability and biodegradability, natural fibers are promising for industrial use in fiber-reinforced composite materials. Porous structures of natural fibers greatly contribute to the excellent sound absorption properties and multilayered composite panels also possess good sound insulation. Natural fiber reinforced composite (NFRC) laminates were manufactured in view of the process requirements of industrial production. Acoustic properties of NFRC, such as absorption coefficient, transmission coefficient and transmission loss, were measured by transfer function method in four-microphone impedance tube. Moreover, a theoretical model of multilayer material system of NFRC was proposed and the predicted results calculated by transfer matrix method are consistent with experimental measurement. This model can be used to predict acoustic properties of multilayered laminate system of NFRC.