Analysis of the dispersion relations and sound transmission loss in an axialli symmetric acoustic metamaterial panel

In recent years, the advent of acoustic metamaterials introduced novel strategies for the front wave manipulation on subwavelength regimes which has thus demanded a continuous effort by several researchers. Previous research by the authors has evidenced the capacity of axially-symmetric acoustic systems to achieve perfect absorption in broadband frequencies, enabled by the critical coupling of nearlocal resonances. Here, we further extend the idea of axially-symmetric coupling by creating a ventilated acoustic metamaterial plate dealing with the front wave propagation and sound attenuation characteristics, making use of dissipative equivalent fluid approaches. This type of acoustic metamaterial is here defined, and the corresponding dispersion relations are analysed as a function of the geometrical characteristics, testing single, dual, and triple resonance cases. Then, a geometrical sensitivity study is performed, demonstrating how the parameters affect the dispersion relations and the respective transmission capacity; it is demonstrated that an interplay between the bandgap phenomena can induce significant averaged transmission loss values of around 50 dB, at tuned frequencies. The obtained results are promising and expand the applicability of these axially symmetric devices in the development of novel compact attenuators with applications in different engineering contexts, especially in building environments