Controlling sound transmission with density-near-zero acoustic membrane network

We demonstrate a design of two-dimensional density-near-zero (DNZ) membrane structure to control sound transmission. The membrane structure is theoretically modeled as a network of inductors and capacitors, and the retrieved effective mass density is confirmed to be close to zero at the resonance frequency. This scheme proposes a convenient way to construct the unit cell for achieving DNZ at the designed frequency. Further simulations clearly demonstrate that the membrane-network has the ability to control sound transmission such as achieving cloaking, high transmission through sharp corners, and high-efficient wave splitting. Different from the phononic-crystal-based DNZ materials, the compact DNZ membrane-network is in deep subwavelength scale and provides a strong candidate for acoustic functional devices.