We all know that electric vehicles are the future.

What comes to mind when you think of electric cars/ buses/ locomotives?

Besides the fact that they are eco friendly and emit fewer greenhouse gases and air pollutants than petrol or diesel cars. I am sure you are also thinking how quiet they are.
That is generally speaking. But how about electric locomotives?
In fact, electric locomotives are kind of loud. Not as loud as Diesel locomotives, the noise is very less as compared to Diesel locomotives, but we will get into a bit of detail to this comparison later on.
The reason for that is the number of equipment, electric motors, transformers, switching circuits and additional equipment to help locomotives operate properly.
Most of the noise comes from the cooling system (fans/blowers). There is a lot of heat generated, therefore, both the transformer and the motors need to be cooled down. Blowers are used in this process, forcing the air through ducts to eventually reach the equipment needed.
You might also hear the compressor which compresses air under specified pressures for the air brakes.
Beside all of the above, the interactions of rail to wheels, is another noise generator at regular speed.
Overall, the combinations of these noises are what causes most of the noise in electric trains.How loud is an electric locomotive compared to the diesel one?
Diesel trains are definitely louder than electric trains because of the noise that the diesel engine makes, which is louder than the electric engine.
There was a very interesting experiment conducted by Victor Harbor, Australia:
“Sound power levels of diesel and electric locomotives on rail loops and and entire trains on spur lines were determined through noise measurements adjacent to rail loops and rail spur lines associated with two different Queensland coal terminals. One of the coal terminals had electric locomotives only on the spur line and rail loop, while the other had diesel locomotives only. “ – Proceedings of Acoustics 2013
Summary of Locations and Parameters