Acoustics Research Centre, The University of Salford, Salford, Greater Manchester M5 4WT, United Kingdom.
J Acoust Soc Am. 2011 Dec;130(6):3736-45. doi: 10.1121/1.3655880.
The acoustical performances of regular arrays of cylindrical elements, with their axes aligned and parallel to a ground plane, have been investigated through predictions and laboratory experiments. Semi-analytical predictions based on multiple scattering theory and numerical simulations based on a boundary element formulation have been made. Measurements have been made in an anechoic chamber using arrays of (a) cylindrical acoustically-rigid scatterers (PVC pipes) and (b) thin elastic shells. Insertion loss (IL) spectra due to the arrays have been measured without and with ground planes for several receiver heights. Data and predictions have been compared. The minima in the excess attenuation spectrum i.e., attenuation maxima due to the ground alone resulting from destructive interference between direct and ground-reflected sound waves, tend to have an adverse influence on the band gaps (BG) related to a periodic array in the free field when these two effects coincide. On the other hand, the presence of rigid ground may result in an IL for an array near the ground similar to or, in the case of the first BG, greater than that resulting from a double array, equivalent to the original array plus its ground plane mirror image, in the free field.
通过预测和实验室实验研究了圆柱元件规则阵列的声学性能，这些元件的轴与地面平行对齐。已经进行了基于多散射理论的半分析预测和基于边界元公式的数值模拟。在消声室中使用（a）圆柱形刚性散射体（PVC 管）和（b）薄弹性壳的阵列进行了测量。对于几个接收器高度，已经测量了没有和有地面的阵列的插入损耗（IL）谱。已经对数据和预测进行了比较。在过剩衰减谱中的最小值，即由于直接和地面反射声波之间的相消干涉而导致的仅由地面引起的衰减最大值，当这两种效应同时发生时，倾向于对自由场中周期性阵列的带隙（BG）产生不利影响。另一方面，刚性地面的存在可能导致靠近地面的阵列的 IL 类似于或在第一个 BG 的情况下大于自由场中双阵列的 IL，相当于原始阵列及其地面平面镜像的等效。
