Broadband sound absorption at low frequencies is always a challenge owing to the strong penetrability of acoustic waves. Combining detuned components, such as coupling curled Fabry–Pérot channels, has been proposed for broadband sound absorption. However, the components of the structure are generally arranged in parallel, so that it is difficult to assemble channels with gradient lengths into a compact and thin absorber. Tube networks, which can be seen as broadband and low-frequency sound absorbers, can circumvent this problem. However, the network absorber can only work at fixed frequencies once fabricated. Here, we propose a tunable low-frequency sound absorber consisting of honeycomb plates and detached chips and fabricate it by additive manufacturing. By replacing chips of the sound absorber, we experimentally validate different sound absorption spectrums. A low reduced frequency model and genetic algorithm are developed to design the chips according to targeted absorption spectrums. Moreover, we theoretically study the impact of radius of tube on sound absorption and extend the two-dimensional network to a three-dimensional structure. The remarkable efficiency and versatility of the tunable network sound absorber may pave the way for programmed absorbing material design.

中文翻译：

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基于增材制造的可调网络吸声器

由于声波的强穿透性，低频下的宽带吸声一直是一个挑战。结合失谐组件，例如耦合卷曲 Fabry-Pérot 通道，已被提议用于宽带吸声。然而，该结构的部件通常平行排列，因此难以将具有梯度长度的通道组装成紧凑且薄的吸收体。可以被视为宽带和低频吸音器的管道网络可以规避这个问题。然而，网络吸波器一旦制造就只能在固定频率下工作。在这里，我们提出了一种由蜂窝板和分离芯片组成的可调低频吸声器，并通过增材制造来制造。通过更换吸音器的芯片，我们通过实验验证了不同的吸声谱。开发了低频降频模型和遗传算法，根据目标吸收光谱设计芯片。此外，我们从理论上研究了管半径对吸声的影响，并将二维网络扩展到三维结构。可调网络吸声器的卓越效率和多功能性可能为程序化吸声材料设计铺平道路。