Hooters: They produce a loud hooting noise on receiving signal from the panel in case of fire. The intensity of sound is high enough to alert the entire area it is meant to cover. Strobes: They are used in areas that restrict noise, they produce a large flash which alerts the surrounding of a fire. These are also helpful for the deaf as they cannot hear the loud noise of a hooter. It also comes in a combination of horn cum strobe, which serves both the purposes. Sounders: They are fixed to the ceilings for alerting a small area in case of a fire emergency.