Active noise control and noise reduction: practical examples

The practical examples of ANC (active noise control) systems are shown and discussed in the paper. Examples shown for active noise reduction headsets, noise cancellation in the duct system, general noise reduction using adaptive algorithm are discussed. The efficiency of the active noise control is 1020 dB for the all cases except of transformer where much more control channels have to be implemented in order to obtain the global reduction of three transformer harmonics. It was shown that global reduction for transformer case could be achieved using anti noise loudspeaker and error microphones separated with one half of wavelength.