Reconfigurable acoustic metamaterials for simultaneous broadband sound insulation and ventilation

Abstract

Research on metamaterials balancing broadband noise reduction and ventilation performance holds significant importance. However, traditional materials exhibit low acoustic energy dissipation efficiency at low frequencies and face greater challenges in simultaneously achieving efficient noise reduction and ventilation. In this work, we propose a subspace-expansion method that introduces additional spatial degrees of freedom via basic substructures and realize a reconfigurable acoustic metamaterial (RAM) with a nested labyrinthine architecture, whose low-frequency insulation band is tunable by varying the number of substructures. The labyrinthine structure encircles a central channel, enabling bidirectional fluid flow. The RAM blocks over 90% (10 dB) and 99% (20 dB) of incident acoustic energy within 352–600 Hz and 377–571 Hz, respectively. Furthermore, a combined RAM formed by serially connecting three RAMs achieves an average sound transmission loss of 33.6 dB over 360–2000 Hz. This work demonstrates considerable application potential in the fields of ventilation noise control.