The Bogen Communications ANS500M Sensor Microphone is an additional microphone for the Bogen Model ANS501 Ambient Noise Sensor, a sensor designed to electronically adjust the level of a page announcement or background music in an area of a building where ambient noise levels are continuously changing. It ensures that page announcements or background music are intelligible even during periods of high ambient noise levels. The ANS501 monitors the ambient noise level through the use of an ANS500M sensor microphone module. Each sensor microphone module includes an adjustable mounting base for precise positioning. One microphone and one power supply are included with the ANS501. Additional microphones may be purchased separately. The control unit is capable of supporting up to four (4) microphones wired in parallel. Wire runs between the control unit and microphones consist of two-conductor cable and can reach 2,000 feet (with 20AWG wire) with no appreciable loss of signal strength.