14 - Sound Attenuation in Ducts

Abstract

Sound attenuation provided through a duct system is the focus of Chapter 14, starting with a discussion of the theory of propagation in ducts with losses and then a focus on lined rectangular ducts. The chapter moves on to unlined rectangular, and then lined and unlined circular, and finally flexible ducts. From there it goes on to discuss end effects, split losses, sharp bends or elbows, sound propagation in plenums, and then silencers. The next section deals with breakout and break-in and the duct transmission losses for these phenomena. Finally duct-borne calculations are shown for the control of duct-borne noise.