Low-frequency broadband sound absorption in a parallel truncated-tail sonic black hole

Low-frequency sound wave attenuation and dissipation are critical factors that limit the application and development of underwater vehicles. Acoustic black holes, as a special type of acoustic metamaterial, possess significant potential for capturing and dissipating sound waves. In this study, a parallel configuration of truncated acoustic black holes (TSBH) is designed, where multiple TSBH units with different configurations are coupled together. This coupling effect allows for broadband low-frequency sound absorption. Initially, the effective medium theory is employed to calculate the effective parameters and sound absorption coefficient of the structure, and the finite element method is used to verify the accuracy of the effective medium theory. A parameter scan is conducted to assess the impact of various structural parameters on sound absorption performance. Additionally, impedance tube testing is performed to validate the sound absorption performance of the structure. The results show that paralleling multiple TSBH models effectively enhances the overall sound absorption performance of the material. Compared to a single TSBH model, the average sound absorption coefficient of the material can nearly double when multiple TSBH units are arranged in parallel.