Speaker
Description
We study the problem of trapping acoustic waves in a waveguide using a local realization of flatband-supporting non-Hermitian interactions. These interactions are implemented via active feedback control, using loudspeakers driven by non-collocated microphone measurements to synthesize the desired coupling within a confined region of the waveguide. The design is inspired by PT-symmetric non-Hermitian lattice models that exhibit flatbands in periodic configurations. Here, we translate this concept to a hybrid continuous-discrete acoustic waveguide system and show that the flatband can still be re-produced. This enables trapping of incoming sound waves within the controlled region, preventing both further transmission and backscattering, while the rest of the waveguide remains uncontrolled. The model is developed analytically and numerically, and demonstrated experimentally in a one-dimensional waveguide.