Broadband sound-absorption of absorbing panel based on Helmholtz and coiled chamber

A subwavelength sound-absorbing panel composed of an extended-neck Helmholtz resonator and a coiled coplanar chamber is presented. The coiled coplanar chamber acts as the backplane of the Helmholtz resonator to produce additional absorption peaks. A theoretical model is developed and a numerical simulation is performed to predict the sound absorption coefficient of the proposed absorbing panel and reveal its physical absorption mechanism. An investigation is also conducted on how the structural parameters of the absorbing panel affect its absorption characteristics. The results demonstrate that appropriately adjusting the structural parameters can yield efficient sound absorption for low-frequency sounds throughout a broad range by employing several units connected in parallel mode. The numerical simulation shows that the energy of incoming sound waves is primarily dissipated through the extended neck and coiled chamber. To confirm the validity of the theoretical model and numerical simulation, an experimental study is conducted to evaluate the acoustic characteristics of the designed samples.