Speaker
Description
Low-frequency sound insulation remains challenging due to the long sound wavelengths, making conventional acoustic materials largely ineffective at low frequencies. This study proposes a novel single-path, space-coiled metamaterial designed for efficient low-frequency sound attenuation. The metamaterial is a 28 mm thick cylinder with a 100 mm diameter, comprising a top cover with an input vent, a bottom cover with an output vent, and a central labyrinthine space-coiled region inspired by the Labyrinth Type Gossembrot. Acoustic waves propagate along a continuous, 1.26 m long path spiraling around an 22 mm diameter central core, with channel widths of 3–3.5 mm, significantly extending the effective acoustic path. Sound attenuation in the proposed structure is governed by Fabry–Pérot resonances along the single continuous path. Sound transmission loss (STL) was computed in COMSOL Multiphysics considering the impedance tube setup according to ASTM E2611-17, including thermoviscous effects. The metamaterial was fabricated using 3D printing, showing excellent agreement between numerical and experimental results. The first resonance occurs at 132 Hz, demonstrating a substantial shift of the resonance behavior toward the low-frequency range. The proposed metamaterial enables integration into building wall panels to reduce transmitted noise.