Two stage implantable microphone devices suitable for use in hearing systems are provided. An implantable microphone device may include a housing including a diaphragm with the housing and diaphragm enclosing a chamber; a microphone coupled to the housing; and a vent connecting the microphone to the...http://www.google.es/patents/US5859916?utm_source=gb-gplus-sharePatente US5859916 - Two stage implantable microphone
