In recent years, metamaterial-structures and Microperforated panel (MPP) absorbers have been proposed as a valid alternative to porous materials for sound absorption in the low frequency range. However, high and broadband absorption cannot be achieved in the low frequency range as required in some engineering applications where large thicknesses of the absorbers are unsuitable. In this work, a deep subwavelength hybrid parallel-arranged MPP and Archimedean-inspired spiral (AIS) absorber is proposed to obtain broadband sound absorption at low frequency (i.e. 400–2000 Hz). The absorption properties are investigated using an equivalent electro-acoustic model and a parametric analysis is performed to optimise the geometric parameters of the device for the desired frequency range. Two parallel arranged MPPs and AIS structures were designed to achieve sound absorption in frequency ranges between 550–1650 Hz and 380–1250 Hz, with a total thickness less than 1/28 wavelength (24.3 mm). In addition, a parallel arrangement of an AIS and a double layered MPP were also considered to achieve absorption in a wider frequency range (i.e. 480–2800 Hz). The prototypes were then fabricated and tested with an impedance tube to evaluate the normal absorption coefficient via the Transfer Function method (TFM). Experimental results show a good correlation with the analytical models, with a absorption coefficient above 60% over the respective frequency ranges. Moreover, absorption peaks occur at the resonance frequencies and higher harmonics of the structures, with measured values above 95%. The low frequency broadband absorption shown by the proposed subwavelength hybrid structures makes the device suitable for many acoustic engineering applications.

近年来，已提出超材料结构和微孔板（MPP）吸收器作为多孔材料的有效替代品，以在低频范围内吸收声音。但是，在某些不适合使用大厚度吸收体的工程应用中，无法在低频范围内实现高吸收和宽带吸收。在这项工作中，提出了一种深亚波长混合并行排列的MPP和阿基米德启发式螺旋（AIS）吸收器，以获得低频（即400–2000 Hz）的宽带声音吸收。使用等效的电声模型研究吸收性能，并执行参数分析以针对所需频率范围优化设备的几何参数。设计了两个平行排列的MPP和AIS结构，以在550-1650 Hz至380-1250 Hz的频率范围内实现声音吸收，总厚度小于1/28波长（24.3毫米）。此外，还考虑了AIS和双层MPP的并联布置，可以在更宽的频率范围（即480-2800 Hz）中实现吸收。然后制造原型，并用阻抗管进行测试，以通过传递函数法（TFM）评估正常吸收系数。实验结果显示出与分析模型的良好相关性，在各个频率范围内的吸收系数均超过60％。此外，吸收峰出现在结构的共振频率和高次谐波处，测量值超过95％。