Mei Zhongjian, Li Xiaodong, Lyu Yadong, Sang Jinqiu, Cheng Xiaobin, Yang Jun
Key Laboratory of Noise and Vibration Research, Institute of Acoustics, Chinese Academy of Science, Beijing 100190, China.
Shanghai Institute of AI for Education, East China Normal University, Shanghai 200062, China.
J Acoust Soc Am. 2023 Nov 1;154(5):3479-3486. doi: 10.1121/10.0022513.
In sound absorbers, acoustic resistance and reactance are usually coupled together and affect each other, which brings difficulties to impedance matching. An impedance decoupling method is proposed to make acoustic resistance and acoustic reactance vary independently. For the same thickness and perforation rate, acoustic reactance of the perforated panel with tube bundles (PPTBs) varies with the diameter of the tube, but acoustic resistance remains constant. Theoretical and simulated results show that a PPTB absorptive unit can exhibit resonance modes with varying damping states through impedance decoupling. It is found that through well-modulation, the PPTB unit in a slightly over-damped state cannot only maintain high sound absorption coefficients, but also expand the absorption peak bandwidth. Utilizing the mechanism of impedance decoupling, a broadband absorber is designed and evaluated by comprising the PPTB and microperforated panel (MPP). Measurement results indicate that it possesses an average absorption coefficient of 85% spanning more than a 3-octave bandwidth from 160 Hz to 1400 Hz with a deep sub-wavelength thickness. The impedance decoupling method helps to implement sound absorbers with highly efficient low-frequency broadband absorption.
在吸声器中，声阻和声抗通常相互耦合且相互影响，这给阻抗匹配带来了困难。提出了一种阻抗解耦方法，以使声阻和声抗独立变化。对于相同的厚度和穿孔率，带有管束的穿孔板（PPTB）的声抗随管的直径而变化，但声阻保持不变。理论和模拟结果表明，一个PPTB吸声单元可以通过阻抗解耦呈现出具有不同阻尼状态的共振模式。研究发现，通过良好的调制，处于略微过阻尼状态的PPTB单元不仅可以保持高声吸收系数，还能拓宽吸收峰带宽。利用阻抗解耦机制，设计并评估了一种由PPTB和微穿孔板（MPP）组成的宽带吸声器。测量结果表明，它在深度亚波长厚度下，在160Hz至1400Hz的超过3倍频程带宽内平均吸收系数为85%。阻抗解耦方法有助于实现具有高效低频宽带吸收的吸声器。
