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 broad-band 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. Failure to meet this requirement implies that the overall system contains an acoustic feedback loop and stability and robustness issues become important. The paper investigates this problem in a one-dimensional sound field (e.g., ducts) using a unidirectional sound wave as the feedforward signal. 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 broad-band noise reductions