When designing a voice alarm system for areas of variable noise levels, which could cause problems with audibility, ambient noise sensors (ANS) should be included. Correctly placed ANS will ensure that all announcements are clearly heard.

The BVRAMB monitors the ambient noise in a given area and automatically adjusts the power of the amplifiers, depending on noise level. This ensures that when an area is at its quietest the level of the announcements/background music will reduce and, similarly, during busy/noisy periods the volume level will increase.

Two BVRAMB units can be wired in parallel on the same input to monitor the ambient noise over a larger area.