Sound diffusion properties of triply periodic minimal surfaces using three-dimensional FDTD simulations

Triply Periodic Minimal Surfaces (TPMS) have been noticed in various engineering disciplines such as biomechanics, heat transfer, and structural mechanics due to their continuous curvature, high surface-to-volume ratio, and compatibility with additive manufacturing. In acoustics, recent research has explored their absorption and bandgap properties; however, their potential as sound diffusive surfaces remains largely unexplored. Addressing this research gap, the present study investigates the frequency-dependent sound diffusion performance of six TPMS geometries using three-dimensional Finite-Difference Time-Domain (FDTD) simulations. The analysis follows the ISO 17497-2 standard and is performed using two complementary models: a high-fidelity “Big Model” and a fast Near-Field to Far-Field (NFFF) approximation. Results show that certain TPMS, such as Costa and Scherk’s Tower, achieve enhanced diffusion at mid-to-high frequencies, while others like Batwing exhibit tunable low-frequency peaks. The absence or presence of a rigid backing is shown to significantly influence diffusive behavior. Despite the reduced computational complexity of the NFFF model, its predictions closely match the full model, enabling efficient parametric studies. Finally, potential application of TPMS are discussed, such as the integration of TPMS-based surfaces into acoustic partition panels for improving speech intelligibility in open-plan spaces.