# Airport Land Art Is (Acoustic) Baffling

According to an article in the Smithsonian magazine, these geometrically arranged hills aren’t landing signs for extra-terrestrials, but instead effectively sound baffles worked into the ground behind a runway at Amsterdam’s Schipol airport.

The 80 acres of hills and valleys are called the Buitenschot ‘land art park’ and supposedly reduce noise in the nearby neighborhood by around 50%. They work by sending the reflections in random directions that would otherwise skip off of the ground, just like anti-echo baffles in a sound studio. A nice touch for the local residents, they also contain jogging trails.

People have made land art before — we particularly like Spiral Jetty in the Great Salt Lake — but as far as we know this is the first land art “piece” that’s also functional.

Beauty is in the eye of the beholder, of course. Unfortunately, as the Smithsonian notes, nobody is beholding it. Because Buitenschot aims to diffuse the takeoff noise coming out of the rear of the planes, they are always flying away from it; passengers don’t get to see it from the air.

## 20 thoughts on “Airport Land Art Is (Acoustic) Baffling”

1. “cut the decibel level of the ambient noise in half” is not a 50% decrease :|

1. RÖB says:

To cut dB in half you have to reduce it to a square root of the original volume in the base of the logarithmic scale – base 10 in this case.

You couldn’t perform that mathematical function without adding a dimension to the environment such as very large underground cavities that have small openings in the field and even then I would expect you could only reach twice the square root of the original volume.

TLDR: A 50% reduction in amplitude is credible. Halving the dB is not credible.

2. Kevin says:

Decibels are logarithmic, and our ears are supposedly the same afaik. But yes, percentages don’t really work well for logarithmic scaling.

3. Ah. That’s in the Smithsonian article. I didn’t think we wrote something so sloppy.

The airport authority says they’re “well on their way to the target of 10dB” off. I’ve seen another source citing 50%, which is 6dB. Those are broadly consistent.

Halving the dBs would be absurd.

1. I don’t judge :)

2. Ivan says:

If you half the sound pressure that would be a 6dB reduction, but halfing the sound power is only a 3dB reduction. Which do you think ?

1. RÖB says:

Well that is the same as a voltage reduction in electronics or -6 dBV (Volts).

It equates to half the POWER which is -3 dBm (power referenced to 1 mW) or in this case dBmO (power referenced to an initial offset) relative to the original SPL (Sound Pressure Level) you mentioned. dB is quite often substituted for dBmO.

But that’s not all.

The white noise from a jet exceeds out hearing range so to measure it correctly (by human perception) it needs to be measured and specified in dBmOP (dB as power referenced to an initial value and weighted psophometrically to human perception of sound).

3. dynamodan says:

“Because Buitenschot aims to diffuse the takeoff noise coming out of the rear of the planes, they are always flying away from it; passengers don’t get to see it from the air.” What about on landing? Aircraft perform both takeoffs and landings into the wind, so these may be visible to passengers upon landing, in fact, the photo looks very much like it could have been taken just off the 09 end of the east-west runway at Schiphol either approaching from the west or taking off toward the west.

1. dynamodan says:

In the satellite photo on google maps, you can tell the wind was southerly at the moment of the shot, as there are two planes at the north end of the runway waiting their turn, and one performing its takeoff roll toward the south. Wow the airport itself is a work of art. Buitenschot would be at right angles to that runway, to the right, from the perspective of a passenger in the plane taking off from the 18 runway.

2. Queeg says:

The structure is located to the southwest of the west most runway, 36L-18R (also known as the Polderban.) The runway is only used for northbound departures and southbound arrivals. (Notice the lack of runway turnoffs at the north end?)

I’ve departed from and arrived on that runway many times and have never seen it – I would guess it’s not visible from the runway, but I can’t say for sure.

4. Mark says:

And I thought my yard was tough to mow!

5. Interesting article, but I think the residents of Dubai might argue about this being the first (or only, as I believe the writer was implying) functional land art in the world…

1. Leithoa says:

The many indigenous cultures that built ritual and burial mounds would further contend that appellation.

1. Mark says:

Are you speaking of cultures indigenous to the Netherlands or Dubai?

1. Fennec says:

The world, obviously.

1. Dave says:

The word indigenous was used incorrectly by Leithoa in this context.

6. echodelta says:

Mound Builders not withstanding, shrubbery and pines should eat up a lot of sound. Shrubs would be a lot more friendly to belly landing than landing on a washboard unless exactly head on to the groove.
Giant phonograph record… ideas… the “train that uses ground effect” , whatever.

7. Ross Hershberger says:

Been in and out of that airport 4 times this year and I never noticed it. My only impression of the area out the window: flat.

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