A modified transfer matrix method for prediction of transmission loss of multilayer acoustic materials

A new experimental approach, herein referred to as a modified transfer matrix method, for evaluating normal incidence sound transmission loss of multilayer solid materials, is presented. As it is the key element for predicting the transmission loss of a material, the original transfer matrix was measured directly via a standing wave tube method. During predictive studies of multilayer materials, the transfer matrices of solid layers were modified in accord with data from the vibration of thin plates and the mass law effect. We validated the feasibility of this method through experiments on several different kinds of materials. This method can be applied in designing multilayer sound insulation materials that are widely used in automotive engineering and building acoustics.