A Study on Output Analysis and Quality Improvement of Micro-Speaker

• Main Authors: Wen-Hsin Hsu, 許文馨
• Other Authors: 王昭男
• Format: Others
• Language: zh-TW
• Published: 2010
• Online Access: http://ndltd.ncl.edu.tw/handle/72537385378913578189

碩士 === 臺灣大學 === 工程科學及海洋工程學研究所 === 98 === An application of feedback linearization control for micro-loudspeakers is presented in this paper. With inverse dynamic processor, signal distortion caused by loudspeaker nonlinearities can be compensated. First of all, the loudspeaker system separates into three parts: electrical, mechanical and radiation to build the classical linear and nonlinear models. Then converting the theoretical model into discrete-time system and using digital processing technique to simulate the output of the loudspeaker system. The theoretical model is verified by comparing the frequency response of real loudspeaker to the numerical result of simulation. The agreement is good. The second part is to investigate the effect of the parameter variation on the output of the loudspeaker. In this study only the transduction coefficient varies with displacement is considered. This nonlinearity will cause unwanted harmonics in the response of loudspeaker. To reduce this nonlinear effect, a feedback linearization method from nonlinear control theory is applied to the nonlinear loudspeaker model. Numerical simulation reveals that the feedback linearization method can cancel the harmonic signals effectively. Finally, the present approach is applied on the nonlinear control of the real loudspeaker. The result is some parts of harmonics are reduced obviously. But some output sound signal seems not be improved under control. This may due to the incorrect values of transduction coefficient. But it still needs a further study.