Influence of Noise Frequency on Secondary Sound Source Layout for a Duct Active Noise Control System

Abstract

The ducts generate noise when the duct equipment works, which seriously affects people's life and work. Active noise control effectively reduces low frequency noise in the ducts. According to the acoustic theory, the optimal secondary sound source location of the duct active control system under different noise frequencies is derived and a duct active noise control system based on virtual error sensing strategy is designed. The single-frequency noise of 300 Hz, 400 Hz…1000 Hz was tested. The maximum noise reduction in the 500–700 Hz range was greater than 10 dB. The theory and experiment results showed that the secondary sound source was arranged at an integer multiple of half wavelength to achieve the greatest noise reduction. The layout rule was applied to a duct fan with a rotational speed of 2600 r/min, and a noise reduction of 11.1 dB was obtained.