Adaptive control of noise at a point in three dimensional space

• Main Authors: Wuu,Hou-Giong, 伍昊炯
• Other Authors: Hong,Hong-Ki
• Format: Others
• Language: zh-TW
• Published: 1994
• Online Access: http://ndltd.ncl.edu.tw/handle/97825469563883135721

碩士 === 國立臺灣大學 === 土木工程研究所 === 82 === We use adaptive control to attenuate the noise at a point in three dimensional space. The adaptive algorithm adopted is the normalized least mean square (NLMS) method. The signal detected by a microphone is used to estimate the demanded output of the speaker which plays the role of a controller, and the system parameter is then updated with the aid of the error signal detected by another microphone, usually called the error microphone. The system is modeled as either a finite impulse response (FIR) filter or an infinite impulse response (IIR) filter. We suppose the property of the system is indefinite, and deduce an adaptive FIR control rule and an adaptive IIR control rule. A geometric point of view is employed herein to see the convergent behavior of the NLMS algorithm, including the convergence of the successive estimated values of the system parameter and the estimated errors in the cases where the output signal of the system is under the influence of noise. According to the theory deduced and the results of numerical simulations and lab experiments, the wideband signal is found most suited to identify the impulse response of the system considered. Our experimental results show that the effect of noise control using the FIR model is better than that using the IIR model.