Excess sound absorption at normal incidence by two microperforated panel absorbers with different impedance
Excess sound absorption at normal incidence by two microperforated panel absorbers with different impedance
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DOI：
10.1250/ast.32.194
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发表时间：
2011-09
影响因子：
0.7
通讯作者：
Motoki Yairi;K. Sakagami;K. Takebayashi;M. Morimoto
中科院分区：
文献类型：
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作者：
Motoki Yairi;K. Sakagami;K. Takebayashi;M. Morimoto
微穿孔板（MPP）吸声器被认为是下一代吸声器最有前途的替代方案之一。然而，它的吸收频率范围仅限于两个倍频程左右，因为它的吸收仅取决于亥姆霍兹共振机制。因此，作者提出了两种不同MPP吸收器并联的组合，并揭示了其在过量衰减方面实现更宽吸收频率范围的潜力。在这项研究中，通过混合的边界元法和模式展开法，作者研究了在两个不同的MPP边界处的阻抗不连续性所造成的过量衰减和使用电声等效电路模型推导出的吸声系数之间的关系。通过对垂直入射吸声系数的测量验证了等效电路模型的正确性，并在实验中结合实验结果讨论了实现宽带吸声的并联布置的腔体结构。
A microperforated panel (MPP) absorber is known to be one of the most promising alternatives of the next-generation sound absorbers. However, its absorption frequency range is limited to around two octaves because its absorption solely depends on the Helmholtz resonance mechanism. Therefore, the authors have proposed a combination of two different MPP absorbers in parallel, and revealed its potential for achieving a broader absorption frequency range in terms of excess attenuation. In this study, by the hybrid method of BEM and a mode expansion method, the authors investigate the relationship between the excess attenuation caused by the impedance discontinuity at the boundary of the two different MPPs and the sound absorption coefficient derived using the electro acoustical equivalent circuit model. Measurements of the normal incidence absorption coefficients are carried out to validate the equivalent circuit model, and in the experiments, the configuration of the cavity to realize the parallel arrangements for achieving wideband sound absorption is also discussed referring to the experimental results.