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Inventor Of The World's Largest Instrument Discusses Physics Behind The Earth Harp

Evan Petersen

by Evan Petersen

Published July 29, 2013

In a recent interview with the NY Times, William Close, creator of the world's largest instrument, discussed the techniques and physics behind the Earth Harp. An incredible spectacle and sound to behold, the harp has been installed over canyons, in amphitheaters and concert halls, and even attached to Seattle's Space Needle and The Colosseum in Rome.

The Earth Harp is a massive stringed instrument with strings ranging in length from 100 to 1000 feet. The harp can be installed at any location sizable enough to accomodate it. The strings are secured to the bridge, then fanned out and anchored to the architecture or landscape. After some fine-tuning, Close stands in front of the bridge and vibrates the strings using gloves covered in violin rosin, turning the location into an echo-chamber and creating an ethereal, cello-like sound. You can hear some of the incredible performances above.

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Check out some choice bits from the NY Times interview below and read the whole thing right here.

So you have on this instrument strings that are 1,000 feet long? More? Less?

With the resonating chamber and bridge resting on the stage then I’ll run a special type of wire that I have specially made, it’s a secret recipe. I run that wire out over the audience and into the architecture somewhere or into the landscape so that the strings are anywhere from roughly 100 to 1,000 feet.

What is the difference in the length of the string? How does that change the sound?

What’s great about the Earth Harp is it is actually based on string length. That has to do with the physics behind the way it’s played. For instance in order to receive a middle C on the Earth Harp, I need a string that’s exactly 40 feet long. So the way I do that if I have a string that’s, say, 100 feet long, is I’ll take a tuning block and mount it to the string 40 feet out from the bridge and that stops the vibration at that point. Now if I want the C below the middle C, I would actually double that. So I would put a tuning block 80 feet out, and the C below that would be 160 and so on.

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Tell me a little bit about how the instrument is played.

The way the Earth Harp is played is I wear gloves with violin rosin, the dust of violin rosin. I crush that up and put that on the gloves themselves. Violin rosin is a sticky substance. And then what I do is I pinch the string and run my hand along it. So I don’t pluck the string or bow it, I actually run my hand along the string. And what I’m doing is I’m actually pushing the vibration in the molecules of the string. It’s referred to as a compression wave. And it’s the same principle actually as running your finger around the edge of a wine glass. In that situation you’re actually vibrating the material itself, and that’s what’s happening with the stings of the Earth Harp.

And does it matter where you’re playing them with your hands in the gloves? If you’re playing it close to the bridge or further away from the bridge do you get different notes?

The way that works is that the closer to the bridge you play you actually get more of what are called harmonics, which are sort of the upper notes above the main tone. So as your hand moves closer to the bridge you still have that main tone, say it’s a C, but you hear more of the upper notes that happen above it, the upper harmonics. It’s actually really beautiful. And then as you move your hand away from the bridge, those harmonics slightly disappear.

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...Were there any technological or engineering complications or obstacles that you had to overcome in building this harp and making it the size that it is?

I’ve explored a lot of different designs for the resonating chambers and I find that the key for a good resonating chamber is to create a space or chamber that has lots of different dimensions in it because all the different notes need different lengths of dimension in order to resonate. So that’s why you see a lot of curves in resonating chambers or diagonals or triangles because it creates an area where the space is getting bigger or smaller in lots of different directions.

The other key ingredient in terms of creating the Earth Harp is I really had to have a clear understanding of tension and tensions structures. So I’ve spent a lot of time on sailboats and I looked at bridges, and architecture that uses tension and really used that as my inspiration.

Does it sound different at each different location or does what it is grounded to have little to do what it sounds like?

Yes, the environment the Earth Harp is set up in definitely plays a role in how it sounds. Whether it’s the materials of the space or the openness of the space, whether it’s outside, inside, you know I’ve had it strung up to the top of a mountain before and the mountain had caves actually in it up at the top, and you can hear the strings from within the caves. So every space is different and every place is a bit of an experiment.

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What’s the next step for the Earth Harp and your performances with it?

I have a team called the Earth Harp collective. It’s a team of musicians that I work with and we use the Earth Harp and a number of my other invented instruments, as well as violin and voice and acoustic and classical guitar and percussion. The music is really beautiful. And then I’m very interested in developing this show concept “1,000 strings,” which is as I was mentioning before the idea of actually putting the audience in a theater that has 1,000 of these Earth Harp strings going everywhere and letting people experience that. I think it would be spectacular. I really hope I get the chance to do it.

You can find more information about William Close and the Earth Harp at their official website.

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