siren
A device which emits a loud warning signal to alert the public in case of a catastrophic event.
A siren is listed as a public amenity for an object when a device is mounted to that object or present on it which emits a loud warning signal to alert the public in case of some catastrophic event, such as a wartime raid, a severe storm, a volcanic eruption, or anything else of that nature. Sirens are often mounted on public buildings such as fire stations.
Sirens differ from loudspeakers, which are used for broadcasting spoken or recorded messages. The sound from a siren is usually a simple tone or pulse with an even or sliding pitch.
The device is installed on or present on the object and supplies a public warning signal. The simple tone or pulse distinguishes its usual warning output from the spoken or recorded content broadcast by an external loudspeaker.