ACTIVE NOISE CONTROL WITH THE ACTIVE MUFFLER IN AUTOMOTIVE EXHAUST SYSTEMS

摘要

This study experimemally demonstrates the use of anactive muffler attached to an automotive exhaust system toreduce exhaust noise. For improving the signal to noise ratio inthe process of estimating secondary path transfer functions, anon-line algorithm in which conventional inverse modeling iscombined with an adaptive line enhancer is used as the controlalgorithm. The active muftler is designed so that the primarynoise and the control sound are propagated as a plane wave inthe outlet. Therefore, the error microphone could be placedoutside the high temperature centers of the tail pipe, and thenoise radiating to the outside could be reduced in the wholearea around the outlet.The control experiment for reducing exhaust noise with anactive muffler is implemented during m-up at no load.Compared with the conventional off-line mew it can beseen from the experimental results presented the proposed onlinemethod is capable of acquiring a reduction of more than 5dB of exhaust noise in overall sound power level.