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题名	小型扬声器的闭箱设计研究：后腔体积的确定与箱壁振动问题
作者	钟旋
学位类别	博士
答辩日期	2005-05-29
授予单位	中国科学院声学研究所
授予地点	声学研究所
关键词	小型扬声器 闭箱设计 T-S参数 板振动 激光测振仪
其他题名	Design of Miniature Closed-box Loudspeakers: The Determination of Back Cavity Volumn and The Problem of Radiation Due to Vibration of Enclosure Walls
学位专业	声学
中文摘要	便携式电子设备中普遍借助小型扬声器播放声信号。其中的小型扬声器单体尺寸一般在1cm级别，具有与普通尺寸扬声器不同的结构和性能特点，在设计与之配合的后腔时，需要加以考虑。本文讨论了小型扬声器后腔设计中的两个重要方面：后腔体积的确定与闭箱壁板振动的抑制。 首先，用传统的等效电路方法研究了闭箱扬声器系统的原理，在此基础上介绍T-S参数方法，模拟了不同后腔的效果。随后，利用等效电路模型、板振动模态公式，以及“有限元-边界元”方法分析了实验模型中板振动的影响。比较了各种方法的精度、结果形式和适用范围。实验方面，进行了频响测试和激光振动测试。对比了坚固箱体、薄板和改良后薄板的性能。 本文的主要工作有三：首先，发现板振动的前3个“奇次-奇次”模态对系统的性能有较大影响。前人的工作曾认为仅有板振动的基频有较大影响，而高阶模态无影响。本文修正了这个观点，认为在箱壁较薄、内阻较低的情况下，(1,3)和(3,1)模态也有较大影响。第二，修正了Tappan的等效电路模型，并将其应用于板振动速度的模拟，得到了符合激光测试的低频仿真结果；三是从扬声器参数出发，利用有限元-边界元方法完成了箱体振动声辐射的仿真，并得到了可用的结果，而此前的文献均局限于讨论有限元、边界元方法中的一种，没有一次性完成“单体-后腔-壁板-声辐射”模拟的成功尝试。 本文的学术价值在于，利用多种手段分析了小型扬声器后腔的设计问题，获得了与实验数据相符的结果，拓展了以上手段的使用领域和范围。本文的实用价值在于，给出了较完整的小型扬声器后腔体积的测量计算方法；针对小型扬声器箱体的振动问题，本文提出的改进方案能有效抑制板振动的声辐射。这有助于便携式电子产品的设计人员了解小型扬声器原理，设计具有更高声品质的产品。
英文摘要	Today, miniature loudspeakers are widely used in portable electronic devices. The miniature loudspeaker unit, with a typical dimension of 1cm, differs from the ordinary loudspeaker unit in structure and parameters, which should be considered in the design of enclosures. This thesis addresses two major aspects in closed-boxed miniature loudspeaker design, one being the determination of the volume of the back cavity, the other being the suppression of radiation due to the vibration of the enclosure walls. Analogous circuit of the closed-box loudspeaker design is analyzed in detail. Based on this, T-S parameter method is introduced to simulate the effect of different back cavity volumes. The problem of the vibration of enclosure walls is studied with analogous circuit, formula of resonant frequencies of plates, and finite element - boundary element method. These approaches are compared in terms of accuracy, form of results and applicable frequency range. In the experimental study, sound pressure level tests and laser scan tests are conducted. The performance of rigid box, thin metal enclosure wall and modified thin metal enclosure wall are compared. Contribution of this thesis include: (1) The first three (odd-odd) mode of the plate have major influence on the performance of the system. Earlier research of the problem suggested that the fundamental mode (1,1) is the most important and only influential factor. However, based on experimental findings, the present study modified this notion in that mode (1,3) and (3,1) also plays significant roles when the damping of the plate is low. (2) The analogous circuit of Tappan is modified and utilized in the simulation of plate vibrating velocity, which goes on well with laser scan tests in the low frequency range. (3) The parameter of the loudspeaker is tested and used in FEM-BEM simulation, and sound radiation of the back wall of the model enclosure is calculated. The simulation result agrees with the test result in general. Former articles focus on either FEM or BEM alone, and no unified FEM-BEM simulation has been attempted before. This thesis may help audio designers in the development of miniature loudspeaker systems with higher sound quality. First a complete method of testing and computing the volume of the back cavity is presented. Secondly, modifications of enclosure walls prove to be effective.
语种	中文
公开日期	2011-05-07
页码	80
内容类型	学位论文
源URL	[http://159.226.59.140/handle/311008/372]
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	钟旋. 小型扬声器的闭箱设计研究：后腔体积的确定与箱壁振动问题[D]. 声学研究所. 中国科学院声学研究所. 2005.

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