Every protected area should be equipped with a fire alarm system. When actuated, the system should sound alarms that can be heard above ambient noise levels throughout the facility.
Visible alarm indicating devices are permitted in critical areas instead of audible alarm devices. The fire alarm should also transmit automatically to the fire department. Any fire detection or fire suppression system that activates should automatically activate the building alarm system.
Fire alarm systems to alert occupants to leave the building are normally operated manually. The alarm-sounding devices themselves should be distinctive in pitch and tone quality from all other sounding devices, and the use of these devices should be restricted to evacuation notification. Vocal alarm systems have been developed and installed in many high-rise buildings.
NFPA 101 mandates voice alarm and communication systems in high-rise buildings. It is, of course, very important that all alarm system devices be distributed throughout a building so as to be heard effectively in every room above all other sounds.
Visible, as well as audible, alarm devices are sometimes used in buildings. NFPA 101 permits flashing the exit signs with the activation of the fire alarm system. In new construction, visible alarms must be provided in addition to audible alarms in most instances.