Characterization of the Magnetic Circuit in a Balanced Armature Receiver

The balanced armature receiver is an electromagnetic transducer used in hearing aids and high-end hearables. The electromagnetic circuit is determining of the inherently nonlinear behavior of the receiver. We will present a scale model of the magnetic circuit that preserves the physical behavior of the original system. The resulting magnetic field of the circuit is experimentally measured to capture how fringing flux and magnetic leakage affect the effective mechanical motion of the armature. We investigate and compare how well a lumped element model can predict the magnetic behavior and validate against a finite element model as well as three sets of measurements: Electrical impedance, magnetic flux and armature velocity.