Electret Noisecancelling Microphone.
D. W. Mackiernan, Alan P. Woodward · Defense Technical Information Center (DTIC) · 1978
This document covers the technical details of advanced development work performed to adapt the electret principle for the purpose of improving noise-cancelling microphones for military use. A major objective was to achieve a flat frequency response over a greater bandwidth and noise cancellation characteristics extending to a higher frequency cut-off point than previously possible with dynamic units. (Author)