Spatially-localized Fano resonance in acoustic metamaterials and its application to frequency-selective earmuffs

Abstract We present a shared-exit Fano acoustic metamaterial for space-constrained applications requiring soundproofing and ventilation. The design features a central orifice surrounded by labyrinthine channels that converge into the orifice, spatially localizing the acoustic interference within the structure. Through numerical simulations and experimental measurements, we demonstrate a reduced downstream interference regime compared to conventional Fano configurations. Based on this concept, we develop a frequency-selective earmuff prototype targeting the 4 kHz range characteristic of industrial grinding operations. The prototype achieves a sound attenuation exceeding 45 dB in the range from 3520 Hz to 4400 Hz while preserving the speech communication band, and experimental validation confirms both its acoustic and thermal performance. The proposed shared-exit configuration offers a practical strategy for implementing Fano-interference metamaterials under stringent spatial constraints.