Noise sensor for COMPACT systems. It communicates with the public address system through a data bus, measuring and sending the level of noise it obtains from the place where it is located. In this way, the system can automatically modify the volume of each zone according to the ambient noise. Includes the microphone capsule in sealed box, audio signal processing circuit and communication module. Through the control software, it is possible to assign one or more sensors to each zone, while adjusting the weighting of each sensor with respect to the area in question, providing a more realistic measurement of the ambient noise level. Each COMPACT matrix allows the connection of up to 16 NS-CAN units. The noise sensor allows the use of an external microphone sensor (not included).