A correction of the insertion-loss for constant sound pressure with flow

Abstract

The insertion-loss is evaluated by B parameter of the four-terminal matrix method as far as constant sound pressure source is concerned. However, the predictions using the equations in the four-terminal transmission matrix method do not reflect a practical phenomenon accurately. In this paper, the correction method to derive the insertionloss based on the Characteristic Curve Method is presented. Correction of the fourterminal transmission matrix method was carried out by rewriting the real and imaginary parts as they depend solely on the flow velocity. Then the result was compensated for by adding the component of the temperature gradient.