A microphone uses an infrared light emitting element and an infrared light receiving element as a proximity sensor. The microphone can avoid the adverse effect of disturbing light without the need for a special optical filter to enable a person (speaker) to be reliably sensed. The microphone includes...http://www.google.com/patents/US20050232447?utm_source=gb-gplus-sharePatent US20050232447 - Microphone
