Active noise control: A tutorial review

Active noise control (ANC) is achieved by introducing a canceling "antinois e" wave through an appropriate an ay of secondary sources. These secondary sources are interconnected though an electronic system using a specific sig nal processing algorithm for the particular cancellation scheme. ANC has ap plication to a wide variety of problems in manufacturing, industrial operat ions, and consumer products. The emphasis of this paper is on the practical aspects of ANC systems in terms of adaptive signal processing and digital signal processing (DSP) implementation for real-world applications. In this paper, the basic adaptive algorithm for ANC is developed and analyz ed based on single-channel broad-band feedforward control. This algorithm i s then modified for narrow-band feedforward and adaptive feedback control. In turn, these single-channel ANC algorithms ar-e expanded to multiple-chan nel cases. Various online secondary-path modeling techniques and special ad aptive algorithms, such as lattice, frequency-domain, subband, and recursiv e-least-squares, ale also introduced. Applications of these techniques to a ctual problems are highlighted by several examples.