An alarm is something used to alert people quickly to something. Most alarms use loud noises and/or flashing lights. Some alarms may use other ways of attracting peoples attention quickly, such as turning off loud machinery, shaking a bed or pillow.

The sound of a fire alarm in a Japanese school.

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Klaxon submarine alarm

The sound of a klaxon alarm on a submarine.

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Types of alarms

Alarm clock - A clock designed to make noise to wake up people.
Burglar alarm - An alarm that sounds if a person tries to enter a building without permission.
Siren on an emergency vehicle (ambulance, fire truck, police car).
Severe weather sirens - Used to warn of severe weather, such as tornadoes or tsunamis.
Klaxon - A type of siren, known for it's distinct sound. Often found on submarines.
Fire alarm - An alarm for warning of fire inside of a building.

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