ASA 129th Meeting - Washington, DC - 1995 May 30 .. Jun 06

1pNS10. Insertion loss studies of a baffle-simple expansion chamber system.

P. Xiao

M. G. Prasad

Noise and Vibration Control Lab., Dept. of Mech. Eng., Stevens Inst. of Technol., Castle Point on the Hudson, Hoboken, NJ 07030

Insertion loss (IL) is the difference of sound pressure levels measured at a reference point without and with a muffler in a duct system. Thus, IL describes the acoustical performance of the whole system which includes source, muffler, and tail pipe. IL studies of a simple expansion chamber has been reported in the literature. However, there are not many IL studies of complicated geometries in a muffler from a system design point of view. This study reports both experimental and analytical work on the influence of a baffle on IL of a simple expansion chamber. The hole diameter and location of the baffler are the parameters of this study. An Altec electroacoustic driver is used as a source for experimental work conducted in an anechoic chamber. The analytical work is carried out using the boundary element method. The results indicate a significant influence (due to the interaction of source and load) on the insertion loss.