Leveraging microelectromechanical microphones inherent matching to reduce noise using multiple microphone elements

Signal-to-noise ratio (SNR) is a critical parameter in the adoption of small scale (~1 mm) microphones for use in hearing aids. As a result, electret microphones have dominated the market since their invention in the 1960’s. Significant effort is being invested to increase the SNR of microelectromechanical (MEMs) microphones near that of electrets. This work covers the approach of using multiple microphone elements to increase SNR. It explores the theory, examines the dependence of the SNR improvement on the matching of the microphone elements, and compares measurements on a single element microphone versus a multiple element microphone. Finally, it examines why the MEMs fabrication process lends itself to this usage and compares the trade-offs in scaling elements versus scaling size.