Low frequency broadband study of Helmholtz resonant cavity with symmetrical structure

Abstract Although traditional structures achieve high bandwidth, they typically require larger designs for optimal performance and are mainly effective at higher frequencies. Suppression of low-frequency noise remains a critical challenge. This study proposes a symmetrical Helmholtz resonant cavity to effectively suppress and regulate low-frequency noise and vibration. The band structure and transmission spectrum were analyzed, and the influence of geometric and material parameters on the Helmholtz resonant cavity’s band gap was examined. Adjusting parameters, including the wrapping layer thickness and cavity taper, reduced the bandgap’s starting frequency from 176.2 Hz to 163.32 Hz. Furthermore, the bandgap width expanded from 503 Hz to 566.32 Hz, the coverage rate rose from 63.60% to 71.61%, and the peak vibration attenuation increased from 80 dB to 96.68 dB.