eli5 Emergency Vehicle Sirens

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What do the different sirens heard from Emergency Vehicles mean? Such as Wail, Yelp, Priority, etc?

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8 Answers

Anonymous 0 Comments

They all mean “get out of my way”. They use different ones different places based on the acoustics of the area.

Anonymous 0 Comments

They all mean “get out of my way”. They use different ones different places based on the acoustics of the area.

Anonymous 0 Comments

They don’t mean anything.

The point is cycling through them is meant to be enough of a tonal change that people don’t tune out the normal siren. If they just used the standard wail a lot of people would likely automatically filter that sound out to some extent given how common sirens are.

Anonymous 0 Comments

They don’t mean anything.

The point is cycling through them is meant to be enough of a tonal change that people don’t tune out the normal siren. If they just used the standard wail a lot of people would likely automatically filter that sound out to some extent given how common sirens are.

Anonymous 0 Comments

I sometimes use sirens for my job. I use the wail tones while driving along a straight or long road, and yelp tones at intersections.

I remember being told that the reason we do this is not only to grab people’s attention, but also because the yelp tone sends the siren in different directions. So, for example, the wail tone will go in a big long wave out the front, and the yelp will go a smaller way out the front, and also out the sides. This helps at an intersection, because there is traffic coming from 4 directions.

There is another siren that my country uses called “hi-Lo” tone, which is literally a high tone, followed by a low tone then repeated. Like what people think of as “European sirens”. I like to use this one when driving on a highway.

Outside of this, the siren is literally just to warn people that 1. You are coming and 2. People need to get out of the way. Apart from the yelp siren use at intersections, I don’t believe there are any particular uses or each type of siren (in terms of what you are responding to) and it just comes down to operator preference.

Anonymous 0 Comments

I sometimes use sirens for my job. I use the wail tones while driving along a straight or long road, and yelp tones at intersections.

I remember being told that the reason we do this is not only to grab people’s attention, but also because the yelp tone sends the siren in different directions. So, for example, the wail tone will go in a big long wave out the front, and the yelp will go a smaller way out the front, and also out the sides. This helps at an intersection, because there is traffic coming from 4 directions.

There is another siren that my country uses called “hi-Lo” tone, which is literally a high tone, followed by a low tone then repeated. Like what people think of as “European sirens”. I like to use this one when driving on a highway.

Outside of this, the siren is literally just to warn people that 1. You are coming and 2. People need to get out of the way. Apart from the yelp siren use at intersections, I don’t believe there are any particular uses or each type of siren (in terms of what you are responding to) and it just comes down to operator preference.

Anonymous 0 Comments

Traditionally the sirens on vehicles were mechanical items. They used systems like alternating between multiple air horns (like the pipes that form an organ) at different pitches, or used systems of spinning and stationary plates or cylinders that would interact and cause air to flow between and around them and create the different and changing pitches.

Different vehicles might use different versions depending on what was practical and possible to mount to different vehicle types, and what different countries and services felt was the most appropriate choice.
This is why sirens were traditionally very distinctive – certain siren types or models would be fitted to police, others to fire engines so you could easily tell them apart, and the same for different countries services.

Modern sirens tend to be electronic instead – essentially just a loud speaker that can be used to play back pre-prepared sounds.
This ability to change the sound means we can change the sounds to suit different purposes. Certain sounds will be better at carrying over long distances, while others will be more immediate and noticeable, but if more limited range. So one siren may be used on a long straight road to give vehicles warning far ahead, and a different one approaching a junction better for grabbing the attention of those nearby who may not have heard the earlier siren from a distance.

The ability to change the sound also helps to gather attention too – when you hear a regular sound for a period of time you start to tune it out as background noise, so stopping that sounds and changing it to a new one helps bring attention back to it.

Anonymous 0 Comments

Traditionally the sirens on vehicles were mechanical items. They used systems like alternating between multiple air horns (like the pipes that form an organ) at different pitches, or used systems of spinning and stationary plates or cylinders that would interact and cause air to flow between and around them and create the different and changing pitches.

Different vehicles might use different versions depending on what was practical and possible to mount to different vehicle types, and what different countries and services felt was the most appropriate choice.
This is why sirens were traditionally very distinctive – certain siren types or models would be fitted to police, others to fire engines so you could easily tell them apart, and the same for different countries services.

Modern sirens tend to be electronic instead – essentially just a loud speaker that can be used to play back pre-prepared sounds.
This ability to change the sound means we can change the sounds to suit different purposes. Certain sounds will be better at carrying over long distances, while others will be more immediate and noticeable, but if more limited range. So one siren may be used on a long straight road to give vehicles warning far ahead, and a different one approaching a junction better for grabbing the attention of those nearby who may not have heard the earlier siren from a distance.

The ability to change the sound also helps to gather attention too – when you hear a regular sound for a period of time you start to tune it out as background noise, so stopping that sounds and changing it to a new one helps bring attention back to it.