Thin sound absorbers with coiled and coupled resonators

摘要

Acoustic metamaterials offer fascinating opportunities for manipulating sound and the development of compact devices with broadband performance. The ability of resonant-based metamaterials to induce slow sound has recently been exploited to design thin sound absorbers at deep subwavelength frequencies. In this work, we show that the combination of the slow sound conditions with the space-coiling and/or coupled-resonator mechanisms allows further reducing the panel thickness and overcoming the narrow-band performance imposed by the resonant nature of the wave dispersion. The space coiling implies here spatial folding of the resonator aimed at reducing the overall structural sizes, while a coupled resonator is represented by a Helmholtz resonator with a cavity partitioned into two or more parts by one or several supplementary necks. We show that the coupled resonator possesses an additional absorption peak at low frequencies, whose frequency can be tuned by varying the resonator geometric parameters. The advantages of the proposed design ideas are demonstrated numerically, and experimental validation for 3D-printed prototypes is envisioned. We hope that the proposed results provide possible directions that could be further investigated and could increase the potential of acoustic metamaterials for industrial applications.