Fig. 2: The experimental environment and the design of the ARMs.
From: Optimizing multi-user indoor sound communications with acoustic reconfigurable metasurfaces
a The experimental environment, which is a furnished room of an irregular shape in the reverberating regime. b A photo of the ARMs consisting of a total of 200 tunable Helmholtz resonators. c Photos of the THRs that form the ARMs. The volume of the THRs can be altered by rotating the internal partition with a program-controlled motor. The upper panels show the motor mounted on a reflective backplate (transparent) and the external view of the THR. The lower panels show the closed and open states. d Experimentally measured reflection phases and amplitude reflection coefficients of the THR at closed (blue) and open (red) states. The black dashed curve plots the phase difference between 2 states. The insets show the mode profiles obtained using finite-element simulation.
