Together with atmospheric and water pollution, noise pollution is threatening human society with vehicles constituting the major source of noise. The available literature on control measures (1, 2, 3) indicates purely reactive mufflers in general are of more use for fixed speed machinery and dissipative attenuators have the ability to filler out acoustic energies over a wide range of frequencies. This paper presents cm attempt made to use a combination of these major types of mufflers fitted in the exhaust line of a four stroke, twin cylinder stationary diesel engine to attenuate exhaust noise to an acceptable level. A sound attenuation of 19 dBA has been obtained for combined reactive and dissipative (Model—M2, loosely packed with glass wool) attenuator through entire the load range without affecting the engine performance and a sound attenuation of 21 dBA has been obtained for reactive (with baffle plate. Model—M3) muffler through the entire load range with a nominal increase in BSFC at higher loads.

1.
Anonymous, Noise Control in Industry, Sound Research Laboratories Ltd.
2.
Anonymous, Handbook of Noise and Vibration Control, 4th Edition.
3.
Munjal, M. V., Acoustics of Ducts and Mufflers.
4.
Harris, C. M., Handbook of Noise Control, McGraw Hill Book Co. Inc., New York, 1957.
5.
Bernake, L. L., Noise and Vibration Control.
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