What was the first warning siren?<br /><br />The first siren was invented by John Robison towards the end of the 18th century as a device to create a piercing sound. The noise is generated by a jet of air being forced through a high-speed rotating disc with evenly spaced holes around its edge.<br />How far can you hear a tornado siren?<br />Outdoor warning sirens are designed to be heard and alert people outdoors to go indoors and receive weather updates from local media. Outdoor sirens can be heard for approximately 1 mile in each direction. However, rain, wind and hail and other factors may affect your ability to hear the sirens.
