Nonlinearities and distortion model of a balanced armature receiver

A balanced armature receiver (BAR) is characterized by small size, high electroacoustic conversion efficiency and high sensitivity. High distortion is caused by the significant nonlinearities when the BAR vibrates at high amplitudes. Four nonlinear parameters representing the nonlinearities are derived from the lumped parameter model (LPM) of magnetic circuit. The iterative algorithm is adopted to investigate the important effect of armature reluctance on the nonlinearities. The nonlinear parameters are simulated accurately by the proposed finite element model (FEM) based on moving mesh and equivalent rotation, considering the nonlinear armature reluctance. An integrated FEM and LPM model is developed for analyzing distortion in the case that the simulated nonlinear parameters are substituted into the nonlinear LPM model of the BAR. The experimental results show that the total harmonic distortion, the second-order and third-order harmonic distortion of the BAR with different load can be predicted correctly by the distortion model.