Have you ever been sitting at a busy intersection waiting for that never-ending red light to finally turn green? Then all of sudden you hear those crazy sirens and you see that fire truck in review mirror, making all sorts of different noises and sounds.
Most of the time when people think sirens they think of the yellow minions going BEE DOO BEE DOO. Which is pretty accurate but fire trucks make other noises as well and for various different reasons.
But it all boils down to getting the bystanders that are driving to pay attention. Here are some different sirens and what they are used for.
For the most part fire trucks have three main sirens and alarms to notify other drivers of their approach. They are the electric siren, the mechanical siren and the air horn. But there are others as well that are increasing in popularity.
Now sirens and other emergency signals have adapted over the years but still follow the basic principal of being as noticeable as possible. Fire trucks date back well before modern motors and were horse drawn. So a simple bell sufficed alerting the public nearby that the fire brigade or company were coming so clear the way.
Now with advancement in consumer vehicles and noise cancellation a basic bell falls way short of being heard on a busy road. Sirens and even emergency lights are becoming louder and brighter in order to gain the attention of nearby drivers. These noises can be jarring but are necessary for the safety of the response to the emergency situation.
This is your typical sound you hear from fire trucks, ambulances, police cars and of course minions. They all use pretty much the same electric siren. This is kind of of a passive siren that does not require any real work for the driver of the fire truck.
The electric siren has a few different tones it can do to break up the pattern to catch the attention of other drivers. Its typically is considered loud but in terms of sirens its on the lower end of volume. Usually an electric siren is equipped with its own set of variety of tones and noises that can be changed at the drivers discretion.
The Federal Q (Mechanical Siren)
This is a huge staple and probably the most traditional sound for a fire truck. Very similar to an air rave siren, the federal Q siren emits a very distinct sound that carries a large distance.
The Federal Q is a brand name, a common one albeit, but the generic term is mechanical siren since it uses a fan or blower to move air to create the loud noise. This is a great siren to use when approaching busy intersections to aid in clearing traffic.
This siren is really used as an accessory with other sirens on the vehicle since it carries so far it can be hard to tell where exactly the sound is coming from.
The air horn
The air horn is exactly that a horn powered by air. This tends to be one stop below a train horn in terms of volume. The air horn in combination with mechanical siren is a great combination for bringing busy intersections to a halt.
Air horns use pressurized air to vibrate an internal diaphragm. This makes the actual noise and the horn, which is the cone shaped ending, amplifies and directs the noise.
The sound is jarring in nature and grabs attention quickly of nearby vehicles. While the distance is not as far as the mechanical siren, it makes up for it being a very loud and sharp sound.
This is a newer style electric siren that works in conjunction with the standard electric siren. Using low frequency sound waves this device allows drivers nearby to not only hear the sirens but to feel them as well.
In the most basic sense they are subwoofers tuned into the sirens to create bass for the siren. This especially useful in smaller emergency vehicles such as police cruisers or a chiefs vehicle. The smaller the vehicle the harder it is to see.
In my experience of using them it definitely grabs the attention of the drivers who are not paying attention to the already loud sirens….and it kinda sounds like a UFO is coming.
Now this is one of the oldest alarms used in the fire service. Way back in the day this is what they alerted pedestrians that they were coming so get out of the way.
Nowadays when a fire truck has it mounted on the bumper it’s for tradition and it looks great for parades. That and a well maintained and polished bell shows pride in the service.
Originally these bells were usually made of brass with an iron clapper. In fact most FDC caps were brass many years ago. Now the bells are chrome plated over brass to protect from tarnishing.
Bells also have a more honorable history in the fire station. It would signal the start of shift and is also used in remembrance of a fallen firefighter. Also known as a Last Alarm.
Lots of different emergency signals.
With vehicles becoming more sound proof by the year the emergency vehicles have to adapt with newer technology that’s including both sounds and visuals. Now sirens are louder and more aggressive with Lights being brighter LEDs. This aids in both audio and visual recognition of other drivers.