Compensating acoustic feedback in feed-forward active noise control systems using spline adaptive filters

Implementation of a feed-forward active noise control (ANC) system in a short duct may cause acoustic feedback between the active loudspeaker and the reference microphone. The conventional filtered-x least mean square (FxLMS) algorithm based ANC systems are not designed to handle this situation. Similarly, an FxLMS algorithm based ANC system fails to effectively mitigate noise when non-linearities are present in the system. In an endeavor to overcome these two limitations of traditional ANC systems, in this paper, we propose an adaptive infinite impulse response (IIR) spline filter for non-linear ANC. The adaptive nature of the spline activation function in the proposed scheme enables the filter to effectively switch from a linear to non-linear nature and vice versa, depending upon the scenario in which the ANC system is implemented.