Progress in ship sound cloaking technology based on acoustic absorbing and insulating metamaterials

The development of ship acoustic stealth technology faces multifaceted challenges from emerging detection methods. Underwater detection technologies are becoming diversified with continuous improvements in detection accuracy and resolution. Traditional acoustic stealth technologies, represented by anechoic tiles, are encountering bottlenecks, such as insufficient low-frequency sound absorption. Acoustic metamaterials, with their unique ability to "control long wavelengths with small sizes," show significant potential in controlling ship vibration and noise. This paper systematically reviews the main technical approaches and bottlenecks of ship acoustic stealth technology. It focuses on the acoustic modulation properties of phononic crystals, membrane-type metamaterials, and Helmholtz-type metamaterials in air, analyzing them from the perspectives of mechanisms and engineering applications. Based on existing research, it further explores the application of metamaterial-based underwater acoustic coatings and outlines future development trends.