Air-Water Acoustic Transmission Enhancement Device Based on Encapsulated Bubble Metasurface.

Efficient acoustic transmission across the water-air interface is fundamental to a wide range of applications, yet it is severely limited by the high impedance mismatch between water and air. Conventional acoustic metamaterials are primarily designed for homogeneous media, and although resonant bubbles are promising, their practical application is constrained by stability issues. Inspired by gas-filled packaging materials, this study presents an encapsulated bubble-based acoustic metasurface for enhancing sound transmission across the water-air interface. We systematically investigate through numerical simulations the effects of bubble size, spacing, height, and distance from the interface on transmission performance. Simulations indicate that the peak transmitted acoustic energy can be enhanced by more than 300 times after accounting for dissipation, and experiments have demonstrated an enhancement exceeding 15 dB within the 340-360 Hz range. Furthermore, we develop an air-to-water acoustic transmission enhancement device (ATED) leveraging resonance effects and with low scattering loss. It achieves a peak transmission enhancement of 23.9 dB, and the optimal transmission frequency can be flexibly tuned by adjusting the immersion depth. In addition, air-water acoustic communication is successfully demonstrated using music signals. This work provides a stable and effective solution for enhancing water-air acoustic transmission, while offering a potential approach to repurposing plastic films to mitigate environmental pollution.