Speaker
Description
This contribution presents a condenser microphone concept based on a segmented backplate, where directional characteristics are obtained from differences in the mean membrane displacement between electrode segments. The approach enables the realization of bidirectional (figure-of-eight) responses without the need for multiple acoustic paths and provides a flexible basis for synthesizing other directivity patterns through signal combination. The segmented-backplate concept and its analytical description build on previously published work and are here extended and further developed.To support the design and analysis of such microphones, an advanced analytical model is introduced. The model describes the coupled behavior of a clamped circular membrane and the thermoviscous acoustic field in the air gap, while explicitly accounting for arbitrary backplate perforation patterns and plane-wave excitation from an arbitrary direction. In contrast to simplified or symmetry-restricted approaches, the formulation captures non-axisymmetric membrane motion and spatially varying pressure fields across a broad frequency range, including frequencies above the first membrane resonance.Analytical predictions are validated against three-dimensional finite-element simulations, showing very good agreement in membrane displacement, air-gap pressure, and frequency-dependent mean displacement. The model further enables accurate prediction of directional characteristics derived from segmented outputs, including their frequency-dependent deviations.The presented framework provides an efficient tool for the design and optimization of condenser microphones with tailored directivity, including extensions toward cardioid and other directional patterns.