Design of large planar diaphragm incorporating multiple vibrators for sound directivity control via FEM and BEM

We have realized a sound directivity control of a large planar diaphragm by controlling the bending vibrations using multiple vibrators. This paper proposes a method to determine the parameters such as the shape and thickness of the diaphragm and the position of the vibrators. In this method, the finite element method (FEM) is used to simulate the diaphragm vibrations and the boundary element method (BEM) is used to simulate the radiated sound. We first validate the simulation results by measuring the actual bending vibrations and sound directivity and comparing them with the simulated results. We then show that metaheuristics are effective in finding appropriate parameters because the sound directivity largely varies in a continuous manner with variations in the parameters.