These microphones are linear, noise-cancelling, dc powered high-gain microphones designed for use on military headband-type or helmet configured headsets at low altitudes or for use in pressure-type oxygen masks at altitudes where the use of an oxygen mask is required and CBR masks for special missions. The microphones are intended for use as a part of existing military and future airborne and ground communication systems that will provide communication of high intelligibility under the extreme noise conditions encountered in military environments.