Synergistic Floatation-Sound Absorption: Piezoshell Foam Architectures for Hydroacoustic Attenuation

Large-wavelength low-frequency sound waves are highly penetrative, and existing acoustic load-bearing structures struggle to achieve effective absorption across different media through pore and molecular chain regulation. The development of high-performance underwater acoustic materials is constrained by the limited tunability of traditional microporous structures and the poor pressure stability of viscoelastic polymers. Here, we present a microporous composite structure enhanced by piezoelectric nanoparticle filling for efficient low-frequency sound absorption. This design integrates porous ceramics with microporous piezoelectric polymers to form a multilayer resonant system, wherein embedded nanocomposites facilitate additional sound reflection, resonance, and interfacial collisions. These interactions synergistically promote both acoustic-thermal and acoustic-electric energy dissipation, enabling high-efficiency low-frequency sound absorption within a compact architecture. The optimized structure achieves a noise reduction coefficient of 0.54, with the onset frequency of the sound absorption coefficient exceeding 0.8 as low as 840 Hz. Under hydrostatic pressure ranging from 0.1 to 2 MPa, the attenuation of the average sound absorption coefficient was only 36.62%, significantly lower than the 75.61% observed in conventional polyurethane. In addition, the acoustic–electric conversion property endowed composites with the capability to sense sound waves, while the composite’s lightweight, stress-resistant, and hydrophobic characteristics support mechanical stability and underwater applicability. This work achieves superior broadband absorption and excellent pressure stability, offering a compact, multifunctional solution for advanced acoustic systems.