Duct-borne sound prediction and control
Cheuk Ming Mak, Kuen Wai Ma, Hai Ming Wong · 2023
Chapter 2 briefly introduces duct-borne sound prediction and control, as there are design guides and handbooks that provide tables and charts for the prediction of transmission noise in air duct. This chapter introduces three types of noise problems that may be encountered in a typical ventilation ductwork system. These are the primary noise, breakout noise, and secondary noise. Primary noise is also known as transmission noise. The source of primary noise in ventilation ductwork systems is fans. Breakout noise is the sound that leaves the system at points other than duct terminations. Secondary noise is also known as regenerated or flow-generated noise and is a type of aerodynamic noise. This chapter provides a stepping stone to the more complicated duct-borne noise problem and prediction methods for flow-generated noise discussed in Chapter 3 .