How many times have you gone to a concert and returned with your ears ringing thinking, “That must have been the loudest sound system in the world”? It turns out that regardless how loud we think a particular sound system is (even in a car audio competition), the winner is the Large European Acoustic Facility (LEAF) in the Netherlands, a facility designed to simulate the environment that a spacecraft will come in contact with during liftoff.
How loud is it? LEAF puts out an incredible 154dB SPL, which is 4 times louder than if you were standing next to a jet engine during takeoff. It’s loud enough to kill you, although you’d be dead already from lack of oxygen in the room (it’s a total nitrogen atmosphere). What’s more amazing is that the room is really large at 900 square feet and 50 foot tall. If that wasn’t enough, the facility will soon boost the power so the output will be up to 158.5dB!
The noise inside the acoustic chamber is automatically controlled and adjusted in real time by an acoustic control system that measures the average across the audio spectrum with up to 32 microphones. This automatic control permits rapid spectrum adjustments, and the desired result can be achieved in less than 30 seconds with a very tight tolerance (<± 0.5dB in the high power bands).
Interestingly, the sound is developed not through software and amplified the way we’re familiar with, it’s generated by the flow of nitrogen over a series of round metal modulators that look like coffee cans (check out this video to see more).
LEAF has actually been around quite a while, having been constructed in 1989. I’m surprised that there aren’t more facilities like this, but it’s not like spacecraft roll of the assembly line every day.
In case you’re wondering, there is a failsafe mechanism built-in to avoid any accidents. The doors to the facility are rigged so that the audio can’t be turned on while they’re open.
Now I wonder what kind of music the scientists play through it when not testing?