Performance evaluation of hybrid active noise control system with online secondary path modeling

A Hybrid Active Noise Control (HANC) system is used to attenuate disturbances in a scenario where a portion of noise is captured by reference sensors. In such scenarios, the secondary path continuously changes due to interference by various electrical equipment used in the Active Noise Control (ANC) system. A practical ANC system should be robust to secondary path effects. In existing literature, the secondary path used in a HANC system is estimated offline. In a real time environment, the secondary path is time varying in nature. Hence, Online Secondary Path modeling (OSPM) is a desirable addition to the design of ANC systems because it significantly improves adaptive filter convergence along with better noise reduction performance. In this paper, we propose modified HANC systems with OSPM as continuous modeling of the noise removes the secondary path effects and the HANC system can be used for real time implementation. To achieve this, we extend the OSPM technique from the Eriksson's method to the conventional HANC system, Sun's cascading adaptive filters algorithm and Akhtar's HANC system. Computer simulations prove that the proposed HANC systems with OSPM improves error modeling accuracy and faster convergence against existing HANC systems where the secondary path is modeled offline. The modified HANC framework is also robust to sudden changes in the behaviour of electrical equipment while ANC operation along with providing improved noise cancelling performance.