Sounders and Strobes
Commercial fire systems have the crucial task of notifying all occupants of a building that a fire condition is present. When activated, systems notify people by using high decibel sounders (horns, speakers or bells) and/or visual outputs (strobes) in varying candelas (brightness of the strobe).
A horn/strobe is the most common sounder for a commercial fire alarm. It notifies audibly with a loud horn and is coupled with a flashing strobe for the hearing impaired. In some older buildings, bells without any attached strobe may be present because at the time of original installation there were no ADA (American Disabilities Act) requirements demanding visual notification.
In bathrooms and in areas where horns are fairly nearby, a standalone strobe would be used. In some buildings where there is an extremely high occupancy or in high-rise buildings, a voice evacuation system may be required in conjunction with fire strobes.