Resonant-scattering hybrid device for multiband acoustic topology valley transmission

This paper proposes a hybrid resonant-scattering device combining local resonance and Bragg scattering to achieve simultaneous topological valley-state transport in multiple frequency bands. This acoustic structure was obtained by integrating two types of Helmholtz resonators arranged in a triangular lattice pattern in an air environment. The Dirac point frequency was dominated by the combined strength of resonance and Bragg scattering, presenting a dynamic change process, according to which four designable Dirac points were obtained at frequencies below 14 kHz. Four independently designed and regulated acoustic topological valley transports appeared along the interface separating the topologically diverse sonic crystals after introducing a rotating-scatterer mechanism, as demonstrated by the numerical calculations and experimental results. In addition, since the valley edge states located in the separated edge bands caused by combining resonance and Bragg scattering were interface dependent, a right-hand rule was proposed to evaluate the interface type. This study paves the way for the engineering application of multiband acoustic antennas, acoustic logic control, and other multifunctional acoustic devices.