This study proposes an acoustic metamaterial featuring a Helmholtz resonator–spiral metasurface (HRSM) to effectively achieve low-frequency broadband sound absorption. A theoretical model is developed to predict the HRSM’s sound absorption performance, and it is validated by numerical simulations and acoustic impedance tube experiments. Results indicated that the spiral metasurface of the HRSM extended the depth of the Helmholtz resonator cavity compared to the Helmholtz resonator, causing the first sound absorption peak of the HRSM to shift ...
