The Bogen ANS500M Remote Microphone is a microphone input for the ANS501 Ambient Noise Sensor. The remote microphone connects to the sensor and literally listens to the fluctuation of a room's ambiance. The sensor then compensates adjusts the paging system's output level accordingly. The ANS500M may be remotely wall or ceiling mounted.  The ANS501 control unit is capable of supporting up to four (4) ANS500M 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.