Sirens Explained – Police Cars Vs. Ambulances (& Fire Trucks)

A siren is a loud device designed to make noise and attract attention.

It is used on emergency and special vehicles, including police cars, ambulances, and fire trucks. They can either be electronic or mechanical, with the electronic variant being the most preferred ones.

Sirens often have different sounds and maybe display different colors that best symbolize the situation at hand.

In this article, we perform a thorough analysis of sirens and how they differ among special/emergency vehicles.

Do Emergency Vehicles All Have Different Sirens?

In the sense of where the departments purchase them from, emergency vehicles often get their sirens from the most common brands (Whelen and Federal).

There are other siren brands, but these two are the most common, per our research.

However, in terms of sounds, emergency vehicles often have different and distinct sounds in cities and states across the country.

In cases where there is more than one emergency vehicle coming through, this helps to avoid dangerous collisions especially at intersections.

So, to avoid such, the emergency vehicles use different siren sounds as well as lighting colors.

This difference may however not be clear to unbothered drivers who just want to get to their destination. For such people, no matter what the siren sounds like, all they hear is “get out of the way”. And that’s fair and safe enough, if you ask us.

Do Police Cars and Ambulances Have Different Sirens?

Truth is, police departments and ambulance services, especially those within the same jurisdictions, often get their sirens from the same source.

The difference between the sounds is so hard to notice.

However, if you are curious, there are some clues, although they may not always be accurate.

Police cars often use the “yelp” sound. This type has a faster cycle than the “wail” sound and is sometimes more effective in getting the public’s attention.

Ambulance vehicles tilt toward the “wail” sound. Sometimes, they use double sirens with different cycles, and the sounds are often deeper.

Generally, ambulance sirens are louder than police sirens because the former are often bigger and enjoy some echo. That’s perhaps the best clue to help them differentiate the two sounds.

Whatever they sound like, the message is the same-make way, an emergency vehicle is coming through.

Related: What Colors Are Police Cars? (Here’s How To Spot Them)

Why Do Cop Cars Have Different Sirens?

As we mentioned before, police cars and emergency vehicles generally have distinct sounds. This helps avoid collisions when there is more than one emergency vehicle in the area.

The different sounds also help get the attention of more persons.

Cops use different siren sounds, and there are up to seven of them, as we’re about to see below:

1. Yelp

The yelp sound typically intersperses between the low and high notes, as indicated in the siren commands. The cops use it alongside fast-flashing emergency lights as a way of alerting the drivers who are ahead of the car.

According to some experienced cops, the “yelp” sound, in most cases, simply means “pull over.”

2. Wail

We mentioned earlier that ambulances often use the “wail” sound. However, it is not restricted, as cop cars use it as well. Just like the yelp, the wail sound alternates between high and low notes but does it slower.

While the “Yelp” sounds like “woo woo woo…”, the “Wail” sounds more like “woooooooooo” at high and low notes. Cops often use it in quieter countryside environments where the protracted sound fits better and can reach more people.

3. Hi-Lo

It has been said very often that police sirens are hardly distinguishable. However, the “Hi-Lo” sound is quite distinct from the other two mentioned earlier. Rather than a “woooo” sound, the Hi-Lo sound more like “ee-oo…”.

You probably wouldn’t find the Hi-Lo sounds in the U.S. though, as they are more popular in Europe. Little wonder, the Hi-Lo is called the “European style siren.

4. Power Call

The Power Call used to be the happening siren as it was the first electronic siren sound made. However, it is less common now and has been replaced by the Yelp, Wail, and Hi-Lo.

This sound is rather monotonous, and it doesn’t feature any alternations between low and high pitches. Just a repetitive and constant “woo woo woo woo woo.”

5. Piercer

The piercer sound is very much similar to the yelp, and only close and patient listening can reveal the difference. Both sounds have the same uses as they are better deployed in urban spaces with incredible traffic.

Giving the sound a patient ear, however, reveals the piercer sound is a lot faster and more urgent than the yelp sound.

6. Howler

While the piercer sounds like the Yelp, the Howler siren sounds like Wail.

The difference, however, is that Howler sounds have lower and softer notes. Basically, the sounds are low-frequency and are best used to alert vehicles directly in front of the police car.

Howler siren sounds are perfect for high-speed pursuits as well as pressing emergencies.

7. Air Horn

The Air Horn is quite distinct from the other sounds. It has a notably long sound that rises in pitch and volume as quickly as it descends in tone. However, it is not as commonly used as the other sounds.

Its effectiveness and distinctness has kept it from becoming totally extinct.

Related: Can Police Cars And Ambulances Change Traffic Lights? (Solved)

Do Police Sirens Sound the Same in All States?

The mere fact that there are at least seven different sirens sound debunks the idea that police sirens sound the same in all American states.

Also, unlike many other countries, the U.S has different police departments across cities and states as opposed to a unified national police department. These departments work with little to zero external interference and definitely do not consult with each other on what sounds to deploy.

However, in a very simple sense, sirens all sound the same. They are loud, jarring, repetitive, and distinct!

Do Police Sirens Sound the Same All Over The World?

In a strict sense, police sirens do not sound exactly the same all over the world. They don’t even sound the same all over the United States, much less, the entire globe.

As we’ve seen before, there are up to seven different sounds, and police departments around the world use a variety of them.

For instance, in Europe, cops mostly use the Hi-Lo siren sound and the “European style” pretty much gives that away. However, police departments in U.S. do not use the “Hi-Lo as much.

Do Ambulances Have Different Sirens?

Emergency services typically do not have sirens tailor-made for them. However, ambulances with medical responders often use the wail and yelp sirens as both types are loud, distinct, and reverberant-just what ambulances need.

Related: Are Police Cars Typically Tuned? (Facts & Answers)

Do Fire Trucks Have Different Sirens?

Fire trucks have different sirens, in the sense that they often use two as opposed to just one. Some even use up to three, all in a bid to warn bystanders, motorists, and the general public of their approach.

The multiple sirens are often very loud and are effective in clearing traffic.

However, fire trucks still use the same sirens as ambulances and police vehicles. Our research revealed that most fire departments in the United States use the Wail sound on their sirens.

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