English
Sirens serve as an acoustic signal of alarms. The outdoor sirens, which should notify people of the alarm, and the internal sirens, which should mainly make the intruder's stay inside the building unpleasant.
Sirens serve as an acoustic signal of alarms. The outdoor sirens, which should notify people of the alarm, and the internal sirens, which should mainly make the intruder's stay inside the building unpleasant.