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History of Police Lights and Sirens: The Terrifying Duo that Scares Away Criminals (Page 3)

As compared to police lights, sirens may be less efficient, mostly because they generate sound that can be easily muffled by any other surrounding sounds, including loud music that the driver may be listening to.

There's an interesting fact to be mentioned about sirens though. The term “siren” has been used in Greek mythology where it had the same meaning with “mermaid”, only that it represented the same thing we've seen in the last sequel of Pirates of the Caribbean: a dangerous temptation.

Sirens however have been brought to life in the 1790s by John Robinson in Scotland and although it now has multiple uses, it was initially intended to serve as a musical instrument. Of course, the initial design was pretty basic, so the first siren was nothing more than a pneumatic tube with two disks.

The principle behind this “innovation” is very simple: one of the disk rotates, the other one is still, so the air from the pneumatic tube creates the famous sound we've all heard because of the interferences that take place in airflow.

Of course, the first designs were pretty troublesome, mostly because installing a standard siren on a car made it heavier. Obviously, aerodynamics wasn't quite an issue at that time, but it was still a pain in the neck for police cars that adopted them in early 1920s and needed to travel as fast as possible.

As the time passed by, the automotive industry and all the other fields evolved at a very fast pace, which means police cars received a lot more efficient equipment.

The first sirens have been replaced with newer technologies, including the current electronic siren which makes a lot more noise and thus helps police officers make themselves noticed much easier.

The first electronic police sirens emerged in 1960s and, as compared to their predecessors, used modulators, oscillators and an amplifier. Just as expected, the sound was transmitted to a speaker that is mounted on the roof and thus increased the overall efficiency of the whole system.

Electronic sirens not only that come with increased efficiency, but they also allowed emergency services to create different patterns, thus helping drivers and pedestrians make the different between a police car, an ambulance or a fire truck.

That being said, here’s a clip that perfectly presents the evolution of police cars over the years:


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