Modeling, identification, and feedback control of noise in an acoustic duct

Although active noise control has been a subject of interest for over 50 years, it has become feasible only with recent technological advances. This paper formulates the problem of noise control in a one-dimensional acoustic duct in a form that lends itself to the application of feedback control theory. In contrast to most of the literature on the subject which uses feedforward techniques, a feedback approach is used. Inconsistencies that appear in previous feedback control models are rectified, controllers are designed using precompensated linear quadratic Gaussian (LQG) synthesis, and experimental verification of the control designs is presented. The experimental results show a reduction of about 5-12 dB over a frequency range from 150-350 Hz.