Abstract In this paper, the sound transmission loss (STL) of multi-layered elastic micro-perforated plates (MPPs) in an impedance tube is investigated using the transfer matrix method under the plane wave condition. The number of MPPs can be arbitrary, and each MPP may or may not have a perforation. For numerical examples, the STLs of single, double and triple MPPs are computed and the accuracy of the proposed method is confirmed by comparisons with the results by the finite element method (FEM). As the micro-perforation ratio increases, the effect of the micro-perforation becomes much greater than that of plate vibration, except at natural frequencies. Accordingly, the STL degrades as the micro-perforation ratio increases, except at natural frequencies. As the perforation ratio increases, the peak frequency of the STL moves toward a higher frequency. In addition, the imaginary term of the impedance acts as an artificial damping term such that the amplitude of the peak becomes smaller. For double and triple MPPs, as the perforation ratio increases, the plate-cavity-plate resonance frequency moves toward a higher frequency, and the dip at resonance becomes blunt due to artificial damping induced by the micro-perforations. It is also observed that when frequency approaches zero, the STL becomes bounded only when all micro-perforation ratios are greater than zero. Otherwise, the STL increases without a limit as the frequency decreases.

中文翻译：

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多层弹性微穿孔板在阻抗管中的传声损失

摘要 本文采用传递矩阵法研究了阻抗管内多层弹性微穿孔板(MPPs)在平面波条件下的传声损失(STL)。MPP的数量可以是任意的，每个MPP可以有也可以没有穿孔。对于数值例子，计算了单、双和三重 MPP 的 STL，并通过与有限元法 (FEM) 的结果进行比较来证实所提出方法的准确性。随着微穿孔率的增加，微穿孔的影响变得比板振动的影响大得多，除了在固有频率下。因此，STL 会随着微穿孔率的增加而降低，自然频率除外。随着穿孔率的增加，STL 的峰值频率向更高的频率移动。此外，阻抗的虚项用作人工阻尼项，使得峰值的幅度变小。对于双重和三重 MPP，随着穿孔率的增加，板-腔-板共振频率向更高的频率移动，并且由于微穿孔引起的人工阻尼，共振下降变得平缓。还观察到，当频率接近零时，仅当所有微穿孔率都大于零时，STL 才会有界。否则，STL 会随着频率的降低而无限制地增加。板腔板共振频率向更高的频率移动，由于微穿孔引起的人工阻尼，共振下降变得钝。还观察到，当频率接近零时，仅当所有微穿孔率都大于零时，STL 才会有界。否则，STL 会随着频率的降低而无限制地增加。板腔板共振频率向更高的频率移动，由于微穿孔引起的人工阻尼，共振下降变得钝。还观察到，当频率接近零时，仅当所有微穿孔率都大于零时，STL 才会有界。否则，STL 会随着频率的降低而无限制地增加。