Gover Bradford N, Ryan James G, Stinson Michael R
Department of Physics, University of Waterloo, Ontario, Canada.
J Acoust Soc Am. 2002 Nov;112(5 Pt 1):1980-91. doi: 10.1121/1.1508782.
A measurement system has been developed that is capable of analyzing the directional and spatial variations in a reverberant sound field. A spherical, 32-element array of microphones is used to generate a narrow beam that is steered in 60 directions. Using an omnidirectional loudspeaker as excitation, the sound pressure arriving from each steering direction is measured as a function of time, in the form of pressure impulse responses. By subsequent analysis of these responses, the variation of arriving energy with direction is studied. The directional diffusion and directivity index of the arriving sound can be computed, as can the energy decay rate in each direction. An analysis of the 32 microphone responses themselves allows computation of the point-to-point variation of reverberation time and of sound pressure level, as well as the spatial cross-correlation coefficient, over the extent of the array. The system has been validated in simple sound fields in an anechoic chamber and in a reverberation chamber. The system characterizes these sound fields as expected, both quantitatively from the measures and qualitatively from plots of the arriving energy versus direction. It is anticipated that the system will be of value in evaluating the directional distribution of arriving energy and the degree and diffuseness of sound fields in rooms.
已开发出一种测量系统，该系统能够分析混响声场中的方向和空间变化。使用一个由32个麦克风组成的球形阵列来生成一个可在60个方向上进行转向的窄波束。以全向扬声器作为激励源，测量从每个转向方向到达的声压随时间的变化，形式为压力脉冲响应。通过对这些响应的后续分析，研究到达能量随方向的变化。可以计算到达声音的方向扩散和指向性指数，以及每个方向上的能量衰减率。对32个麦克风的响应本身进行分析，可以计算出混响时间和声压级的逐点变化，以及阵列范围内的空间互相关系数。该系统已在消声室和混响室的简单声场中得到验证。该系统能够按预期对这些声场进行表征，既可以从测量结果进行定量表征，也可以从到达能量与方向的关系图进行定性表征。预计该系统在评估到达能量的方向分布以及房间内声场的程度和扩散情况方面将具有价值。
