Prediction and measurement of the four-pole parameters of a muffler including higher order mode effects

In this article, transfer matrix parameters and the transmission loss (TL) have been obtained using a numerical tool (SYSNOISE) for a simple expansion chamber muffler with stationary medium and these have been compared with the experimental results obtained by means of a recently developed test-element-reversal method. There is a good agreement between the numerical and the experimental results. This indicates that the higher-order mode effects are implicitly captured by the experimental technique even though it is based essentially on the plane wave theory.