Feedforward active noise controller design in ducts without independent noise source measurements

Feedforward control architectures have been widely used in active noise control systems to achieve broadband noise reductions. The basic principle of the control algorithm requires that the feedforward signal, usually the noise source, be independent from the actuator's output. Fail to meet this requirement implies that the overall system contains an acoustic feedback loop and stability/robustness issues become important. This paper investigates this problem in a 1D sound field (e.g., ducts) using a unidirectional sound wave as the feedforward signal. The controller design based on a distributed parameter model is studied. Several experiments are conducted to illustrate the design procedure as well as verify the effectiveness of broadband noise reductions.