In this chapter, the reader is introduced to:
noise reduction, NR, and Transmission Loss, TL, of muffling devices;
diffusers as muffling devices;
classification of muffling devices as reactive and dissipative;
acoustic impedance for analysis of reactive mufflers;
acoustic impedance of orifices and expansion chambers;
analysis of several reactive muffler types;
pressure drop calculations for reactive mufflers;
lined duct silencers as dissipative mufflers;
duct break-out noise transmission calculations;
lined plenum attenuators; and
directivity of exhaust stacks.
Muffling devices are commonly used to reduce noise associated with internal combustion engine exhausts, high pressure gas ...