Engine exhaust noise being one of the major contributors towards environmental noise pollution, the design and analysis of exhaust mufflers has been a crucial area of research in the field of engineering noise control. Additionally, there exists significant literature towards designing silencers for reducing fan noise in ventilation and air-conditioning systems. This NPTEL course presents for the first time, a set of dedicated lectures on the theory of exhaust mufflers used for reciprocating internal combustion engines as well as ventilation ducts, and so on. While a basic background in Acoustics is desirable, the course begins with fundamentals including the detailed derivation of the 1-D wave equation before moving to the more involved case of 3-D propagation in waveguides and associated concepts. This is followed by an introduction to the terminologies common in mufflers as well as the basic elements constituting acoustic filters including elctro-acoustic circuit analogies and 1-D or plane-wave analysis.
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