A Study On Adaptive Active Noise Control In Enclosed Space

The interior noise in enclosed space has been one of the important indexes used to evaluate the environmental comfort. Usually, the passive de-noising method in enclosed space, such as sound absorption, and sound isolation, etc, have good effect on the noise in middle and high frequency band, but little in low frequency band.An adaptive active noise control (AANC) system in enclosed space is researched in this paper. An AANC system controller and its program code are developed, and an experiment with this system is also carried out. This study has provided a beneficial discussion to application of the AANC system in enclosed space. The main works in this paper are as follows:The algorithm and realization of the AANC system have been researched in this paper. Based on the analysis of the adaptive filter and algorithm, a program for single channel AANC is finished. Using FIR filter structure and LMS realize an AANC system. The simulation of the system is carried out with MATLAB, and how to choose some control parameters of the algorithm, such as the order of Filter and convergence factor, is also discussed.On the basis of the above-mentioned simulation analysis, a real-time AANC system is established. In this AANC system, the heart of the controller is a digital signal processor (DSP), and the algorithm is Least Mean Square (LMS) adaptive filter algorithm. Weight coefficients of LMS algorithm are adjusted according to feedback of residual error sound signal at the position in enclosed space. Some test results of AANC system are obtained, and the test results are also analyzed.