Speaker
Description
Nonlinear distortion is an inherent limitation of condenser microphones, originating primarily from the nonlinear change of capacitance between the diaphragm and the backplate. In single-backplate designs, this effect leads predominantly to second-order harmonic distortion, which can dominate the total harmonic distortion at high sound pressure levels. In contrast, dual backplate configurations inherently suppress even-order nonlinearities due to their differential structure; however, residual distortion remains as a result of geometric and electrical asymmetries between the two sides of the diaphragm.This contribution presents a unified approach for describing and reducing nonlinear distortion in single- and dual-backplate condenser microphones, applicable to classical and MEMS designs. The approach is based on low-order nonlinear models of the microphone output, derived from the capacitance variation, which reveal a common structure of the distortion mechanisms despite the differences in design.Based on this unified description, we propose a simple signal-domain nonlinear distortion correction method. The technique relies on a single parameter that can be obtained either from physical microphone properties or from a straightforward measurement procedure, and can be implemented in analog or digital signal processing with negligible computational cost.The results demonstrate that the proposed method provides substantial reduction of harmonic and intermodulation distortion in single-backplate microphones, while also enabling further improvement in dual backplate designs beyond their intrinsic suppression of even-order nonlinearities. The presented approach offers a practical tool for improving the linearity of both single- and dual-backplate condenser microphones.