A fire alarm system warns people when smoke, fire, carbon monoxide or other fire-related emergencies are detected. These alarms may be activated automatically from smoke detectors and heat detectors or may also be activated via manual fire alarm activation devices such as manual call points or pull stations. Alarms can be either motorized bells or wall mountable sounders or horns. They can also be speaker strobes which sound an alarm, followed by a voice evacuation message which warns people inside the building not to use the elevators. Fire alarm sounders can be set to certain frequencies and different tones including low, medium, and high, depending on the country and manufacturer of the device. Most fire alarm systems in Europe sound like a siren with alternating frequencies. Fire alarm electronic devices are known as horns in the United States and Canada and can be either continuous or set to different codes. Fire alarm warning devices can also be set to different volume levels.
Norwich (/ˈnɒrɪdʒ, -ɪtʃ/ (About this soundlisten)) is a city in Norfolk, England, situated on the River Wensum in East Anglia, about 100 miles (160 km) north-east of London. A city since 1094, Norwich is the county town of Norfolk and unofficially seen as East Anglia's capital. From the late Middle Ages until the Industrial Revolution, Norwich was the largest city in England after London and one of the most important. The present-day population of the city is about 142,000.