| 题名 | 有源声吸收终端的研究 |
| 作者 | 李明锋 |
| 学位类别 | 博士 |
| 答辩日期 | 1999 |
| 授予单位 | 中国科学院声学研究所 |
| 授予地点 | 中国科学院声学研究所 |
| 关键词 | 自适应滤波 系统辨识 有源声吸收终端 有源控制 双传声器法 |
| 中文摘要 | 自适应有源吸收终端是声有源控制的一个应用。它是使次级声源在管道的终端变成一个声的吸收器，从而使得该管道成为一个行波管。这里提出的声有源吸收终端系统由初级声源、次级声源、管道系统和两个传声器组成。通过处理两个传声器的信号以获取自适应滤波器的误差信号。该误差信号代表了实际的终端的声学阻抗与要达到的声学阻抗的差。这里要达到的声学阻抗应该等于空气中的特性阻抗。因为只有这样才能使管道终端成为一个声的全吸收器。本自适应系统利用LMS算法在TMS320C25D上实现。本文的第一章简单叙述了声有源控制的历史发展及其当前的发展状况。第二章介绍了自适应滤波器的有关概念和系统辨识的有关知识。本文的第三章对管道中的声传播作了理论分析，并对管道中的声控制理论基础作了基本介绍。为了使大家对有源吸收终端有所了解，在本文的第四章，介绍了有源声吸收终端的有关理论和知识，并对其实现中的一些关键问题作了分析和解决。由于实验测量的需要，在第五章中简单介绍了双传声器法测量某些声学性质的理论依据。本文的第六章对自适应有源声吸收终端的系统进行了实验探讨，详细比较、讨论了滤波器阶数、步长、采样频率以及两个传声器之间距离对控制效果的影响。最终指出了这些因素在该系统中不是影响控制效果的主要因素，主要因数是两个传声器之间的一致性。最后，还对一定带宽的白噪声作了初步控制。本文的最后总结了全文的工作，指出了可以进一步开展研究的方向。 |
| 英文摘要 | Active sound absorber is an application of active control of sound. It makes use of the secondary acoustic source as a sound absorber, then makes the standing wave tube a travelling wave tube. The system proposed here consists of primary loudspeaker, secondary loudspeaker, two microphones and a tube. The error signal which denotes the difference between the real acoustic impedance and the desired acoustics impedance of the termination, is obtained by processing the signals from the two microphones. The desired acoustic impedance should be equal to the air specific impedance, this is because the termination would be a perfect sound absorber only under this condition. This adaptive system is implemented on TMS320C25D by LMS algorithm. The first chapter of this thesis reviews the history of active control of sound and latest development. After the introduction of related concept of adaptive filter in the second chapter, system identification is introduced. The third chapter presents theoretical analysis of sound propagation and its active control in the duct. In order to make everyone have concept on the active termination, the theoretical analysis of active termination is described. And many key problems are analyzed and solved in the fourth chapter. For the purpose of measurement during the experiments, the fifth chapter is assembled by theoretical analysis of the measuring method with microphone pair. In the sixth chapter, results of experimental investigation on adaptive active sound absorbing termination are presented. The effect of the length of the filter, step, and sampling frequency as well as the relative distance between two microphones are discussed in detail. The results showed that these factors were not the main factors which affected the control result, and the main factor was the consistency of two microphones. At last, the preliminary result of control for noise was also obtained. At the end, main progress made in the thesis is concluded, possible areas deserving further researches are discussed. |
| 语种 | 中文 |
| 公开日期 | 2011-05-07 |
| 页码 | 53 |
| 内容类型 | 学位论文 |
| 源URL | [http://159.226.59.140/handle/311008/644]  |
| 专题 | 声学研究所_声学所博硕士学位论文_1981-2009博硕士学位论文 |
| 推荐引用方式 GB/T 7714 | 李明锋. 有源声吸收终端的研究[D]. 中国科学院声学研究所. 中国科学院声学研究所. 1999. |
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