Numerical Study on the Transient Response of a Condenser Microphone

The vibrating of a condenser microphone diaphragm due to incident pressure causes changes in the capacitance and the energy stored in the volume of the microphone. One of the most important parameters that must be determined very precisely for any microphone is the amount of this displacement due to the executed pressure on the diaphragm i.e., mechanical sensitivity. Thus, in this paper, the generalized equations describing the motion of the diaphragm and the Reynolds equation for compressible gases have been solved in transient mode to determine with precision the mechanical response of the microphone. Unlike the past static and quasi dynamic simulations, the Reynolds equation that is used to calculate the damping and stiffness of the air near the diaphragm is considered in nonlinear form. The numerical frequency response obtained for a condenser microphone has been compared with experimental results that exist in the literature. The numerical results obtained indicate a very good accuracy of the code. The effect of the damping and stiffness coefficient on the frequency range, which is very important in designing a practical microphone, is also studied in detail. Such a dynamic analysis, unlike the past numerical static simulation, gives a deeper view into the reasons of the nonlinearity of this important measuring transducer.