Estimation of the absorption performance of multiple layer perforated panel systems by transfer matrix method

The absorption performance of single layer perforated panel system has been usually estimated by equivalent electro-acoustic circuit analysis based upon the analogy between electric circuit and acoustic system. In the case of multiple layer perforated panel system, however, the transfer matrix method is more convenient than the equivalent circuit analysis. in this paper the transfer matrix method widely used for the one-dimensional acoustic analysis of engine exhaust muffler is presented. The absorption coefficient is estimated from the overall transfer matrix obtained by multiplying unit transfer matrices for perforated panels or airspaces. The proposed transfer matrix method is confirmed by comparing the estimated absorption coefficient with the measured value. In addition, the effect of dimension and arrangement of the perforated panels on the acoustical performance is discussed.