Performance comparisons between a singlechannel feedforward ANC system and a singlechannel feedback ANC system in a noisy-enviroment classroom

Adaptive or Active Noise Control System (ANC) is now widely used in many applications. The problem of interference or noise cancellation is one of the main focuses of the ANC solutions. In this paper, two classic ANC systems called a single-channel feedforward system and a single-channel feedback system will be simulated in MATLAB/Simulink environment for a demonstrative university classroom. This circumstance becomes an interesting issue since the aforementioned classroom is located right next to one of Asia Pacific's largest international airport in Bangkok City, Thailand. A very lousy-noise environment occurs when the time of airplane taking off and landing. Unfortunately, such a noisy environment happens almost every other minute on average. The main idea of this paper is trying to lower the level of the noise during those critical times in the classroom. Two simple ANC systems are brought into account here to see how they perform in resolving the problems in this particular circumstance. The least mean square (LMS) method is used for updating the weight vector in ANC control block diagram in order to achieve the optimal weight vector resulting in minimal errors. How to find bounds on the step size, how to estimate the rate of convergence and the steady-state errors of the proposed LMS method are also elaborated in this paper. The simulation results between two ANC systems will be presented in terms of noise attenuation capabilities and system performances. The discussions and the conclusions presented in this research paper will be used for further analysis to improve the selected ANC system performance before implementing in the real environment in a very near future to come.