Sound transmission through a plate with additive acoustic black holes

Additive acoustic black hole (ABH) plates are composite structures in which an ABH plate with two perpendicular power-law indentations is attached to a host one. This composite design has proven to be very effective in reducing the vibration of the host plate. In addition, the sound radiation from the composite plate can be significantly suppressed when a point mechanical force is applied to it. This paper examines the performance of additive ABHs in improving the acoustic transmission loss (TL) between two resonant cavities. It is shown that the TL is significantly improved for most frequencies due to the combined effects of added mass and damping. However, in certain frequency bands, additive ABHs can perform worse than a bare homogeneous plate. This is attributed to the resonance of the thin air layer between the ABH plate and the host plate. Possible solutions to this problem will be explored in forthcoming studies.