Transverse coupled resonances for ultrathin lightweight acoustic metamaterials

Innovations in acoustic metamaterials increasingly focus on optimizing sound insulation capabilities while addressing manufacturing and integration challenges. Previous studies have explored coupled resonance mechanisms in multilayered structures, where resonators are aligned along the direction of wave propagation. While these approaches provide enhanced sound transmission loss (STL) over broadband frequency ranges, they often require increased panel thickness to achieve the desired insulation. This study introduces a novel approach based on transverse coupled resonances, where the resonators are arranged in the same plane, i.e., perpendicular to wave propagation, by exploiting bending effects in the metamaterial design. By implementing these mechanisms in a single layer, the resulting panel’s thickness and weight are significantly reduced, simplifying the manufacturing process. The proposed transverse coupled-resonances acoustic metamaterial (TCAM) is validated numerically and experimentally using impedance tube measurements, with prototypes achieving 60 dB of attenuation over a broad frequency range around 1000 Hz. Further parametric studies show the potential for enhanced sound attenuation at even lower frequencies with thinner and lighter designs, paving the way for customizable soundproofing solutions tailored to specific application requirements. • Exploiting bending effects to trigger transverse coupled resonances. • Practical design via transverse coupled-resonances acoustic metamaterial (TCAM). • Numerical and experimental validation of the TCAM via impedance tube measurements. • Six times thickness reduction compared to equivalent standard coupled-resonances panels. • Ultrathin (2.1 mm) and lightweight (5.7 kg/m 2 ) TCAM panels based on aluminum and steel.