This paper proposes a subwavelength hierarchical honeycomb structure (SHHS) with a compact lateral dimension and double-band perfect absorption in low frequencies. Unlike the conventional micro-perforated panel (MPP)-honeycomb sandwich absorber, this structure has an additional internal honeycomb with a perforated wall. Therefore, there are two resonant cavities in the SHHS to realize multiple absorption peaks. Analytical, numerical, and experimental investigations are performed to study the proposed system's acoustic performance in absorption. The SSHS is simplified into four parts and its analytical model is constructed by combining various analytical models by acoustic-electro analogy. The analytical model is presented to explore the physical properties of sound absorption and the influence of parameters, which has been validated by comparisons with the numerical model, and the experimental data is measured by an impedance tube. It is found that the main incident energy is lost by the inside hole, which is different from the conventional absorbers with surface MPP. Moreover, the side length of the internal honeycomb can adjust the resonant frequencies to achieve an absorber with the subwavelength. A SSHS is designed with a perfect absorption at 320 Hz whose thickness is 1/31 of the resonant frequency wavelength. The SHHS has excellent potential for noise control engineering applications.

中文翻译：

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亚波长分层蜂窝结构的声学性能：分析、数值和实验研究

本文提出了一种具有紧凑横向尺寸和低频双波段完美吸收的亚波长分层蜂窝结构（SHHS）。与传统的微穿孔板 (MPP) 蜂窝夹层吸收器不同，这种结构有一个额外的带穿孔壁的内部蜂窝。因此，SHHS 中有两个谐振腔以实现多个吸收峰。进行了分析、数值和实验研究，以研究所提出的系统在吸收方面的声学性能。SSHS被简化为四个部分，其分析模型是通过声电类比将各种分析模型组合起来构建的。提出了分析模型来探索吸声的物理特性和参数的影响，通过与数值模型的对比验证，实验数据由阻抗管测量得到。发现主要入射能量被内孔损失，这与具有表面 MPP 的传统吸收器不同。此外，内部蜂窝的边长可以调节谐振频率，以实现具有亚波长的吸收器。SSHS 设计为在 320 Hz 处具有完美吸收，其厚度为共振频率波长的 1/31。SHHS 在噪声控制工程应用方面具有极好的潜力。内部蜂窝的边长可以调节谐振频率，实现亚波长吸收体。SSHS 设计为在 320 Hz 处具有完美吸收，其厚度为共振频率波长的 1/31。SHHS 在噪声控制工程应用方面具有极好的潜力。内部蜂窝的边长可以调节谐振频率，实现亚波长吸收体。SSHS 设计为在 320 Hz 处具有完美吸收，其厚度为共振频率波长的 1/31。SHHS 在噪声控制工程应用方面具有极好的潜力。