Rotatable phononic crystal with multiresonant scatterers for acoustica switching applications

This study presents an acoustic switch based on a sonic crystal (SC) with multiresonant scatterers arranged in a square 2D lattice. The scatterers feature Helmholtz res- onators (HRs) tuned to different frequencies. A 90° rotation of all scatterers enables switching the interaction between Bragg bandgaps (Bragg- BGs) and Helmholtz res- onator (HR) bandgaps, creating selective frequency filtering and wave propagation control. The research targets low to mid frequencies (500-2500 Hz), an underexplored range in current studies. The structure, made via costeffective 3D printing without infill to reduce absorption, is both simple and practical. Tests in an anechoic chamber reveal a notable 20 dB contrast in acoustic insulation. This design offers potential applications in noise reduction for urban and industrial settings, adaptive acoustic systems, sensors, and acoustic energy harvesting.