This paper presents the result of an experimental investigation designed to study the effect of high-intensity sound on muffler element performance. Five prototype mufflers were built and tested over a wide range of frequency and intensity. The mufflers were chosen as being representative of basic single-element and combination reactive mufflers. The apparatus consisted of an acoustic transmission line driven by an electromagnetic sound source and terminated anechiocally. Attenuation data are presented superimposed on curves derived from linear-acoustic theory. Conclusions are stated for expansion chamber mufflers at higher sound pressure levels (SPLs) than could be produced by the test equipment by using constriction tube data and acoustic similarity between these elements. It is shown that the expansion chamber muffler will operate as a linear element when subject to incident SPLs of 165–180 dB depending on muffler attenuation. Mufflers containing resonator elements show no deviation from a linear theory when subject to SPLs of the order of 160 dB except at points near a resonant frequency