Broadband sound absorption performance and high mechanical strength are major concerns for designing a microperforated plate (MPP) absorber, which is generally difficult to achieve for a single-layer MPP with straight holes. A MPP was proposed with variable cross-sectional holes, including large dents on one side, grooves on the other side, and intermediate micro-slits. The beneficial effects of the special geometrical features are thoroughly discussed and experimentally validated. Models to calculate the acoustic impedance are established, and acoustic behaviors within holes are simulated. It was found that the micro-slits could provide necessary acoustic resistance for impedance matching and very low reactance to expand sound absorption bandwidth. The large dents or grooves could provide the necessary thickness with negligible acoustic impedance to enhance plate mechanical strength. This research helps to implement a single-layer MPP design with good acoustical and mechanical performance.

中文翻译：

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变截面微孔板的声学特性

宽带吸声性能和高机械强度是设计微孔板 (MPP) 吸声器的主要问题，这对于具有直孔的单层 MPP 来说通常是难以实现的。提出了具有可变截面孔的 MPP，包括一侧的大凹痕、另一侧的凹槽和中间的微狭缝。对特殊几何特征的有益效果进行了彻底的讨论和实验验证。建立计算声阻抗的模型，并模拟孔内的声学行为。研究发现，微缝可以为阻抗匹配提供必要的声阻和非常低的电抗以扩大吸声带宽。大的凹痕或凹槽可以提供必要的厚度，而声阻抗可以忽略不计，以提高板的机械强度。这项研究有助于实现具有良好声学和机械性能的单层 MPP 设计。