Acoustic switch based on rotatable sonic crystal with multiresonant scatterers

This research introduces an acoustic switch based on a Sonic Crystal (SC) containing multiresonant scatterers. The SC operates in a square 2D lattice configuration with scatterers containing Helmholtz resonators (HRs) tuned to different frequencies. By rotating all scatterers by 90°, the interaction between the Bragg bandgaps (Bragg BGs) and the HRs' BGs can be modified, allowing selective frequency filtering and control of wave propagation. Although SCs operating at low frequencies have been widely investigated, the implementation of reconfigurable acoustic switches in the low-to-mid frequency range (500–2500 Hz) remains scarce. This is one of the novelties highlighted in the present study. The simplicity and cost-effectiveness of the 3D-printed structure, coupled with its hollow design that minimizes absorption, enhances its practicality. Experimental validation conducted in an anechoic chamber shows a significant change in acoustic insulation performance, with a maximum contrast ratio of 20 dB. This design opens up new possibilities for noise reduction in urban and industrial environments, adaptive acoustic environments, acoustic sensors, and even acoustic energy harvesting.