Development of woofer microspeakers used cellular phones

In this paper, two important performance characteristics, SPL and 1^st resonant frequency, are analyzed for woofer microspeaker. For SPL and resonance analysis of microspeakers, magnetic force acting on the voice coil is determined by Lorentz law and electromagnetic FEM analysis. Harmonic analysis of diaphragm vibration and acoustical analysis are also followed using FEM to determine surface velocity of the diaphragm and sound pressure level. Noting that magnetic flux linkage is affected by vibrating voice coil, coupling between mechanical and magnetic analysis should be also considered. The simulated result of the proposed analysis is also compared with the experimental result for woofer microspeaker.