Siren Sound Effects have one aim. To alert us, make us pay attention and get out of the way in an emergency. We are more ready to get out of the way of a police car, fire truck or ambulance when we hear their sirens, rather than just seeing the lights.
There is something about the siren that just grabs our attention. This is partly due to the fact that it uses one of the three elements of sound. It uses Pitch. The siren is used on all emergency service vehicles as it is the most effective sound to alert us to their presence and location.
If we hear an ordinary sound over and over again, our brain quickly recognizes that the sound is the same. When this happens we become bored and/or tired of the sound and start to ignore it or blank it out. This is the last thing we want when trying to alert people in emergencies.
The pitch constantly rises and falls. Rising pitch creates tension and falling pitch creates relaxation. This has an emotional effect on us. Changing between these two opposite states make us stay alert.
Emergency service vehicles often switch between different types of siren. This is an extra way of alerting us. These are known as...
The wail has the longest cycle between high and low pitch. It`s often used in rural locations and on long stretches of road where there isn’t much traffic.
The yelp has a medium rate cycle. Usually used when the emergency vehicle is approaching intersections.
The piercer has a high speed cycle rate and is designed to be used in areas of heavy traffic where motorists either don`t hear the siren or refuse to move out of the way. A manual horn can also be used at the same time.
This combination of all three siren sounds is mostly heard when an emergency vehicle runs into busy traffic in a street or town. They use all three in sequence to maximise their chances of being heard.
Used mostly in Europe, it`s thought this siren allows motorists to better locate where the sound is coming from. It is often used by the ambulance service when behind busy and slow traffic. The Hi-Lo siren is used with or instead of the piercer (phaser) siren. Both have a similar effect.
The hardware control units fitted inside the emergency vehicles have buttons and switches, and allow for manual or automatic operation.
Used during the 2nd World War to alert civilians of air bombing strikes. It`s an instantly recognizable and distinct type of sound.