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The motor sequence was organized as follows: after a control period lasting 500 ms, the animal was informed that a preparatory period (PP) was beginning by a preparatory signal (PS) consisting of diffuse sound and light.


Thus the sound pressure level distribution in a diffuse sound field can be calculated more precisely and easily.


Computer simulation model for room diffuse sound field


Mirror and diffuse sound scattering by a twodimensional wake in a continuously stratified fluid


The creation of quiet zones in a diffuse sound field due to a multipole spherical primary source by means of a radially vibrating surface set in the side of a rigid sphere (secondary source) is investigated in this article.

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 Recently the finite element method has been applied to the engineering acoustics. For example, it has analysised the acoustics field in irregular shaped room, the forced vibration problem of the electroacousitic transducer, and applied to evaluated performance of the reactive muffers. In this paper the finite element method is) demonstrated to applied for the solution of the wave equation. We determined the frequencies of normal modes of the irregular shaped room. By comparing the results for the linear function... Recently the finite element method has been applied to the engineering acoustics. For example, it has analysised the acoustics field in irregular shaped room, the forced vibration problem of the electroacousitic transducer, and applied to evaluated performance of the reactive muffers. In this paper the finite element method is) demonstrated to applied for the solution of the wave equation. We determined the frequencies of normal modes of the irregular shaped room. By comparing the results for the linear function and cubic polynomial function and the convergences of eigenvalue. Calculating on two dimensional models. It has proved that the irregularity of the room shape is not influence the diffuse sound field in the room.  近年来,有限元法已经在工程声学中应用。例如,分析不规则房间内的声场,分析电声换能器的振动问题以及用来评价抗性消声器的特性等。本文讨论用有限元法求解波动方程。用有限元法计算了不规则形状房间的简正频率。比较了线性插值函数和三次插值函数的计算结果和本征值的收敛性。通过二维模型的计算,证明了房间形状的不规则性对室内扩散声场没有影响。  The acoustical behaviour of low rooms is investigated. The problem is simplified assuming:(1) the ceiling to be uniformly covered by sound absorbing material.(2) the floor to be distributed by a lot of sound diffusers.It is supposed that the sound field can be divided into three parts relating to (1) direct sound, (2) 1st reflecting sound at the ceiling, and (3) scattering sound respectively. The scattering sound field is assumed to be nonuniform and non isotropic.For... The acoustical behaviour of low rooms is investigated. The problem is simplified assuming:(1) the ceiling to be uniformly covered by sound absorbing material.(2) the floor to be distributed by a lot of sound diffusers.It is supposed that the sound field can be divided into three parts relating to (1) direct sound, (2) 1st reflecting sound at the ceiling, and (3) scattering sound respectively. The scattering sound field is assumed to be nonuniform and non isotropic.For the sound field generated by a point source putted on the floor, the relation between the sound pressure level and the distance is derived. An approximated formula is given on the form L_p={L_W20lg(2r/h) (r≤h/2) L_W(11+9a)lg (2r/h) (4h>r≥h/2) where L_p is the sound pressure level; L_W is the sound power level; r is the distance between the source and the listening point; h is the height of the room; a is the sound absorbing coefficient of the ceiling for random incidence.For the sound field generated by a lot of sources distributed uniformly on the floor, an equivalent room constant of unit area is introduced, and the formula to calculate the sound pressure level is reduced to the same form as that in the completely diffused sound field.  本文对顶面吸声扁平空间中的稳态声场作了较深入的理论分析。文中把声场视作由直达声、顶面一次反射声和多次散射声三部分声场迭加而成,引进适当统计假定后,严格地解出了点声源辐射噪声时的声场和底面均布大量噪声源时的声场,并得出了相应的切合实用要求的近似计算公式.理论分析与实测结果作了比较,两者良好相符。  The sound attenuation of a rectangular enclosure placed in a diffuse sound field was predicted by using Statistical Energy Analysis (SEA). The variation of sound with the thickness of the enclosure wall was computed and the effect of the acoustical absorption in the enclosure on the attenuation was also shown and discussed.  本文用统计能量分析的方法对一个放在扩散声场内的矩形隔声罩的声衰减进行了预测,计算了隔声罩声衰减随壁厚改变的变化,并讨论了罩内声吸收对声衰减的影响。   << 更多相关文摘 
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