Sound Insulation Properties of Thin Plate with Embedded Two-dimensional Acoustic Black Hole

The acoustic black hole (ABH) effect can be achieved in thin-walled structures with specific power-law-profiled thickness, in which the phase velocity of bending waves theoretically diminishes to zero. At present, researches about sound insulation properties of structure using ABH effect are still in its preliminary stage. As a sound insulation structure, its integrity is indispensable, and the sound insulation ability needs to satisfy the laws of mass density. However, the ABH indentation significantly reduces the mass and stiffness of the plate, which make the sound insulation properties very complicated. In this study, the sound insulation properties of two ABH plates, one with multiple conventional ABHs and the other with multiple modified ABHs with a uniform platform at the center of indentation, were considered for sound insulation. The characteristics of sound radiation and transmission loss of these ABH structures were quantitatively analyzed using finite element method and compared with those of uniform plate. The simulation results showed that the two plates with embedded ABHs had lower acoustic radiation and higher sound transmission loss than the uniform plate. The modified ABH structure outperformed its counterpart in sound insulation performance. Finally, the noise reduction phenomenon using ABH effect was verified by experiments.