Police vehicles have been using sirens as a way of communicating to the public as well as other officers on duty for decades now. While being primarily used to alert pedestrians and other car-bound civilians of the urgency of which the police officer is traveling, other less immediate situations warrant the use of a police siren.
What are the different types of police sirens? And how do you tell the difference between these sirens?
There is more than one type of police siren, these sirens, or sounds, are as follows: Yelp, Wail, Hi-Lo, Power Call, Air Horn, Piercer, and Howler. These different types of police siren sounds not only help officers distinguish between each other when multiple emergency services are in the same area but also serve different purposes when not congested together.
What are the origins of police sirens?
Police sirens have been in use since the early 1960s where they replaced silver bells, usually mounted somewhere in the front of the police vehicle. In fact, according to igg.org.uk,
“Police and other emergency vehicles were fitted with silver bells, mounted singly or in pairs, usually low down at the front of the vehicle, usually off-set to the right or left (fire engines often had them on the roof). The bells were replaced by sirens from 1963 when rotating blue lights appeared. The police are as constrained by the law as anyone else (more so in many ways) and the law stated the position the blue light had to be in and that it had to rotate.”
Police sirens were invented in the late 18th century. The Scottish Natural philosopher John Robinson invented the siren and attempted to implement it as a musical instrument in the year 1790, though due to its harsh, shrill tone, it was not used in the musical world for long.
The name siren comes from Greek mythology, a siren was a beast that was said to lure sailors in with their beautiful singing to ultimately take them to their deaths. Unlike sirens from this mythology, the siren created by John Robinson was not quite the beautiful sound they were looking for.
The original siren invented used a crank that produced the sound when cranked continuously, releasing a piercing and brassy sound when used.
Are There Different Types of Siren Sounds?
Although the average person generally wouldn’t recognize the difference between the varying siren sounds, there are a few distinct sounds that are used in modern siren devices. The different sounds of police sirens vary in frequency, tone, decibels, speed, and sound depending on their urgency and purpose. Here are the different siren noises:
The wail sound slowly alternates between a Hi-Lo unbroken tone. It is considered one of the most commonly used tones by police officers and other law enforcement agencies alike. This wail sound gives off a slow but piercing sound like a (woooooOOOOooooo) style noise.
Although still urgent, it is designed to be used in different circumstances such as alerting traffic to give the right-a-way, inform civilians that they are being pulled over for traffic violations, and providing another sound to ensure that they can stand out from other emergencies services in the general area.
The yelp, like the wail, alternates between the Hi-Lo tone. The difference is that it does so rapidly, informing those around them that they must provide the needed right-a-way, get to safety, or assist in making an emergency stop.
This yelp sound generates a (woo-WOO-woo-WOO) when activated by the police officer. The main reason this noise is used is to show the urgency in which the officer is needing to proceed. It should be considered serious and pedestrians and road users should immediately move out of the way.
The Hi-Lo siren is not so similar to the Yelp and Wail sounds as it does not bring the same “urgency” to the situation. Although this is a commonly used sound by police officers, it is used in alternation with the yelp and wail sounds to better help distinguish between other emergency vehicle sirens or even when performing a traffic stop.
This Hi-Lo sound produces an (ee-oo-ee-oo) style sound and although noticeable, isn’t used as frequently as the yelp and wail are.
This air horn sound is quite interesting. Although it is not often used anymore in cop cars – it was all but replaced by the yelp, wail, and other sounds – it is one of the only pneumatically powered sirens on the modern mechanical siren systems used today. This means that when all the other electronic sounds are not able to be used, this pneumatically powered siren can be.
The air horn rises quickly in tone and volume, then slowly gets quieter again. This is similar to the emergency horns used by the local fire departments and other likewise buildings to alert whole towns of impending dangers. It is a long and piercing sound so when it is heard it is known by all.
The power call is also not as frequently used – yelp, wail, and Hi-Lo have all but taken over as the primarily used sounds – this sound has a very monotonous tone to it. This kind of police siren sound remains the same in tone and frequency and makes a (woo-woo-woo-woo) sound.
The howler sounds similar to the wail however, it does have a notable low-frequency tone designed to be felt near the police vehicle operating it. For instance, in urban areas if a police officer is in heavy traffic and the cars directly surrounding them haven’t quite noticed they were trying to get by, this low-toned howler sound can greatly assist them in getting their attention by producing this sound. Allowing all surrounding them to feel it as well as hear it.
Finally, the piercer sound imitates the yelping sound but due to its higher frequency and more rapid delivery, it is better suited to be used in smaller, more urban environments. Especially in heavy traffic or other likewise settings.
What Are the Different Types of Sirens Used For?
The primary functions of police sirens are to alert civilians and other vehicles on the road of an impending emergency that requires them to give police officers the right-a-way. In other cases, these sirens could be used for quite a few other situations also. Here is a list of some of the most important scenarios sirens are used for:
- Routine traffic stops – These traffic stops are not always followed by sirens when a police officer is signaling to a driver to pull over. Instead, they may use their warning lights if they believe this is enough to grab the driver’s attention. Moreover, if the driver has not immediately been alerted it is very possible to use the siren to make them aware of the situation.
- High-speed pursuits – when on a high-speed pursuit the road is always safer when there are no other vehicles. However, this is seldom the case. Using your sirens could mean keeping civilians out of harm’s way or potentially causing accidents. Sirens are a major factor in getting cars on the road to pull over or make way during these situations.
- Traffic safety – have you ever seen police directing traffic during a car crash on the road? They don’t always use sirens to do so but it has been needed from time to time to help alert drivers that are in a blind spot to the accident. Without the siren, they might have added to the already existing accident.
- Vehicle escorts – vehicle escorts could mean escorting anyone from the president or government officials to civilians with a broken-down vehicle just trying to get off of the road. Whatever the case, using sirens in this scenario alerts everyone around that they are in the vicinity and need the right-a-way. Partnered with their warning lights this makes for a good combo to keep everyone alert to their presence and help them get off the road safely.
- Emergency calls – We did just touch on this, but I thought it would be good to provide some details. If a police officer is called to a hit and run, robbery, murder, or any other serious call, they need to be able to get there as fast as possible. Using the wide range of their sirens to alert everyone around them that they need to go mixed with their warning lights is generally considered enough to do the trick and have them on their way, even in congested traffic.
Types of Police Sirens – Final Thoughts
Police sirens are used for a multitude of functions and situations. Without them, they would likely not get very far, and the purpose of a police officer might be mostly null. They need to be able to get where they are going to serve and protect the communities they work for. The different types of police sirens used are by far one of the most important tools in their arsenal and they are certainly better off with them. Just imagine seeing police officers driving around with a bell attached to their police car instead of the sirens! That would be a sight to see.