A feedforward hybrid active noise control system in the presence of sensor error

In an active noise control (ANC) system, frequencies of the reference cosine and sine waves generated according to the online sensor information may be different from those of the primary noise to be suppressed, if the sensor contains error due to fatigue, aging etc. This difference, called frequency mismatch (FM), will severely deteriorate the performance of the system even though it is quite small. In this paper, three adaptive schemes are introduced for a feedforward hybrid ANC system, which are capable of effectively reducing the FM and thus making the system robust and immune against sensor error. Extensive simulations are conducted to confirm the effectiveness of the proposed adaptive schemes as well as the performance of the modified system.