The zone module has been designed to be housed in the Switching Unit and is provided with specific diagnostic electronics which monitors the operation of the amplification chain and, in case of fault of the amplifier, switches the line on to the backup amplifier. Control is individual on each single amplifier and each single speaker line. Breakdown or short circuits of the speaker line are also detected. Faults detected by the module are immediately sent over to the CSE Central Unit that activates alarm sound and messaging. The zone module includes an additional alarm input and an output relay contact for generic use. On-board micro switches are provided for code configuration, diagnostics on- off over amplifier and speaker line, backup service on-off, relay activation. The zone module provides connections for standard 100V power amplifiers (input and output), 100V speaker line and return loop, 0-NC-NA output relay contacts, one additional alarm input and the background noise detection unit model MRR.