天津体育中心扩声系统设计

本文简要介绍天津体育中心总体扩声系统的构成，并分别对主馆和大练习馆在扩声系统设计中的特点作了详细的说明。对各自建筑结构特点，容易产生和声学缺陷所采取的措施进行了阐述。     

A review of commonly used analytical and empirical formulae for predicting sound diffracted by a thin screen

This paper reviews some useful analytical and empirical formulae that are used for the calculation of sound diffracted by a barrier. A brief historic overview of the study of spherical waves diffracted by a rigid half plane is presented also. The physical principles of sound diffraction by a thin plane are explained. The mathematical expressions are cast in a convenient form for ease of numerical implementation. Accurate analytical solutions are expressed in terms of standard mathematical functions that can be computed readily. Among the approximate solutions quoted, quite a few empirical formulations are adequate for most engineering purposes. The information presented in this paper should also be helpful for those who are interested in the study of sound diffracted by a barrier in a room or in a long industrial space.     

用时空线分析多普勒效应

采用描述波源运动，观察者运动及声波在静止空气中以声速传播的三组时空线，用几何方法导出多普勒公式，并通过时空线相交分析多普勒效应中观察者接收声波信号的时序及周期，着重讨论了一般文献中未曾涉及的不同条件下多普勒效应的结果及其物理意义。     

声学实验及部分声学量的测量

根据超声波在损耗介质中的淮驻波效应，对声速测量实验的内容进行了重新设计，丰富了机械波实验的内容和实验数据处理手段。     

Analyse and sound image localization experiment study on multi-channel planar surround sound system

I.IntroductionAnidealplanarsurroundsoundsystemshouldreproduceanaturalanddistinctimageandshouldnothavetheeffectofAnagepositi9ndistortion.Itshouldalsohaveagoodeffectoverawidelisteningarea)agoodcompatibilitywith8tereosystem.ItshouldnotrequiremanytransInissionchannels.InthispaPeritisproposedthataseriesofplanarsurroundsoundsystemstomeetaboverequlremellts.II-ThereproductionsignalsoftheperfectplanarsurroundsoundsystemFirstthecharacteristicsofaperfectplanarsurroundsoundsystemareanalysed.There-prod…     

Partial molar isentropic compressibilities and volumes of selected electrolytes and nonelectrolytes in dimethylsulfoxide

Precision densities and sound velocities for solutions of selected univalent electrolytes and nonelectrolytes in DMSO have been measured at 25°C, and apparent molar isentropic compressibilities and volumes evaluated. The data were extrapolated to infinite dilution to obtain standard state partial molar quantities, K _s,2 ^° , and V ₂ ^° . Values of V ₂ ^° and K _s,2 ^° for alkali metal halides in DMSO are very similar to those in water. The results confirm conclusions derived from data in water and other nonaqueous solvents that K _s,2 ^° and V ₂ ^° for alkali metal halides are strongly dependent on solvent compressibility. K _s,2 ^° becomes more negative and V ₂ ^° decreases as solvent compressibility increases. Attempts to determine ionic K _s,2 ^° values suggest that a significant dissymmetry exists between ₄P⁺ and ₄B^– in DMSO, whereas in water and MeOH, these large ions appear to behave similarly. Ionic V ₂ ^° values support this conclusion. Steric hindrance in the DMSO molecule is believed to be responsible for this dissymmetry.     

声速综合测量仪的设计与应用

本文分析了声压驻波原理，介绍了声速综合测量仪的设计方法，并给出了较精确的测量结果。     

相位调制型光电音频检测方法的分析计算与仿真

分析了相位调制型音频光电检测方法的可行性,对四步移相法测量声音的光电转换方法进行了计算与分析。结果表明,该种光电检测方法在声音的光电检测应用过程中,振动膜片和探测器位置定位的选择对检测精度起着决定性的作用。该环节直接影响整个检测系统的声音频谱范围和动态范围。     

驻波法测定声速实验的matlab模拟

在驻波法测定声速实验中,根据发射器和接收器之间合成声场的位移波动方程和声压波动方程,用matlab程序模拟了声场和声压的振幅和初相位分布,并对模拟结果进行了分析和讨论。     

Transmission of sound through a pair of rectangular elastic plates

^** Email: f.leppington{at}ukonline.co.uk Two thin elastic plates, which may have different physical parameters,occupy the parallel regions 0 < x < a, 0 < y < b,z = – d and 0 < x < a, 0 < y < b, z = 0, ina Cartesian coordinate system, where the separation distanced is much less than the dimensions a and b. The plates are simplyconnected to a structure that occupies the rest of the region– d < z < 0. The side walls (x = 0 or a, 0 <y < b, – d < z < 0 and y = 0 or b, 0 < x <a, – d < z < 0) are taken to be acoustically soft;the surfaces z = – d and z = 0, outside the rectangularregions occupied by the plates, are taken to be acousticallyhard. Light compressible fluid (air) is in each of the half-spacesoutside the plates and in the rectangular region between them.A sound field is induced by a high-frequency plane wave. Allowanceis made for a small element of damping in the fluid trappedbetween the plates, as well as damping in the plates. Estimatesare derived for the transmitted power, averaged over a frequencyband and with respect to all incidence directions, in the asymptoticlimits of small fluid loading and high frequency. For the casewhere the two plates have identical physical properties, detailedasymptotic estimates are given for the form of the peaks inthe transmitted power, at a discrete set of operating frequencies,both above and below the plates' coincidence frequency.