To enhance the low-frequency broadband sound absorption, we propose an absorber filled with porous material and establish a relative acoustic model. Based on the critical coupling condition, a Helmholtz absorber was designed to achieve perfect sound absorption at 172 Hz by the complex frequency plane method. Considering the weak adjustability and acoustic impedance of the Helmholtz absorber, we devised four absorber filled with porous material units that can achieve perfect sound absorption at discrete frequencies between 400 and 488 Hz with a thickness of only 51 mm. A composite absorber filled with porous material was designed by arranging four absorber filled with porous material units in a coplanar manner. The broadband perfect sound absorption of the composite absorber filled with porous material was subsequently verified by simulation and experiment. The thickness of the composite absorber filled with porous material is only 1/18 of the wavelength corresponding to the perfect absorption frequency, and it shows excellent subwavelength characteristics. The theoretical acoustic model of the composite absorber filled with porous material and the complex frequency plane method can achieve a more efficient design of broadband perfect sound absorbers. The composite absorber filled with porous material not only realizes low-frequency broadband perfect sound absorption but is also lightweight and easy to fabricate. This demonstrates the composite absorber filled with porous material structure has great potential for application in low to mid frequency noise control.

为了增强低频宽带吸声，我们提出了一种填充有多孔材料的吸声器并建立了相对声学模型。根据临界耦合条件，设计了亥姆霍兹吸收器，以通过复频平面方法在172 Hz处实现完美的声音吸收。考虑到亥姆霍兹吸声器的弱可调性和声阻抗，我们设计了四个装有多孔材料单元的吸声器，它们可以在400至488 Hz的离散频率下实现完美的声音吸收，厚度仅为51 mm。通过以共面方式布置四个填充有多孔材料单元的吸收体来设计填充有多孔材料的复合吸收体。随后通过仿真和实验验证了填充有多孔材料的复合吸声材料的宽带完美吸声性能。填充有多孔材料的复合吸收体的厚度仅为对应于理想吸收频率的波长的1/18，并且显示出优异的亚波长特性。填充多孔材料的复合吸声体的理论声学模型和复频平面方法可以实现宽带完美吸声体的更有效设计。填充有多孔材料的复合吸声器不仅可以实现低频宽带完美的吸音效果，而且重量轻且易于制造。