Insertion loss studies on models of automotive exhaust systems

Transmission loss, noise reduction, and insertion loss are the three main characteristics used to describe the performance of a muffler in an automotive exhaust system. Of these characteristics, insertion loss is the most useful. Unlike transmission loss and noise reduction, insertion loss is dependent on both source and radiation impedances. In this paper, source and radiation impedances were measured. The insertion loss of exhaust systems was predicted using theoretical values of radiation impedance and measured values of source impedance. Comparisons of predicted and measured insertion loss are given for various source and radiation conditions. So far the investigations are confined to an electroacoustic driver source and an expansion chamber muffler.