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<nettime> Sound dunes: Desert resonance / Sonic harddrive
Geoff Manaugh on Tue, 20 Sep 2005 18:46:45 +0200 (CEST)


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<nettime> Sound dunes: Desert resonance / Sonic harddrive


*Sound dunes: Desert resonance / Sonic harddrive*

"Sand dunes in certain parts of the world are notorious for the noises they make," the New Scientist <1>
reports, "as sand avalanches down their sides. Some [dunes] emit low powerful booms, others sound like
drum rolls or galloping horses, and some are even tuneful. These dune songs have been reported to last for
up to 15 minutes and can sound as loud as a low-flying aeroplane."

To test for the causes, properties, and other effects of these sand dune booms, "Stéphane Douady of the
French national research agency CNRS <2> and his colleagues shipped sand from Moroccan singing dunes back
to his lab to investigate." There, Douady's team "found that they could play notes by pushing the sand by
hand, or with a metal handle."

They performed, in other words, the transformation of a sand dune ? and, by extension, the entire Sahara
desert, indeed any desert ? even, by extension, the rust deserts of Mars ? into a musical instrument.

Music of the spheres, indeed.

"When the sand avalanches, the grains jostle each other at different frequencies, setting up standing
waves in the cascading layer, says Douady. These waves reinforce one another, making the layer vibrate
like the surface of a loud speaker. 'What's funny is that in these massive dunes, only a thin layer of 2
or 3 centimetres is needed to set up the resonance,' says Douady. 'Soon all grains begin to vibrate in
step.'"

Douady has so perfected his technique of dune resonance that he has now "successfully predicted the notes
emitted by dunes in Morocco, Chile and the US simply by measuring the size of the grains they contain."
The music of the dunes, in other words, was determined entirely by the size, shape, and roughness of the
sand grains involved, where excessive smoothness dampened the dunes' sound.

I'm reminded of the coast of Inishowen, a peninsula south of Malin Head in the north of Ireland, where the
rocks endlessly grind across one another in the backwash of heaving, metallic, grey Atlantic waves. Under
this constant pressure of the oceanic, the rocks carve into themselves and each other, chipping down over
decades into perfectly polished and rounded spheres, columns, and eggs ? as if ideal, Archimedean solids
<3> or the nested orbits of Kepler could be discovered on the Irish ocean foreshore ? all glittering. The
rocks, I later learned, were actually semi-precious stones, and I had a kind of weird epiphany, standing
there above the hush and clatter of bejewelled rocks, rubbing and rubbed one to the other in the
depopulated void of a coastal November. It was not a sound easy to forget.

Because the earth itself is already a musical instrument: there is "a deep, low-frequency rumble that is
present in the ground even when there are no earthquakes happening. Dubbed the 'Earth's hum', the signal
had gone unnoticed in previous studies because it looked like noise in the data." <4>

"Competing with the natural emissions from stars and other celestial objects, our Earth sings like a
canary ? it drones on in a constant hum of a gazillion notes. If it were several octaves higher, and
hence, audible to the human ear," <5> it could probably get recorded by the unpredictably omnidirectional
antennas of ShortWaveMusic <6> and... you could download the sound of the earth.

*Free Radio Interterrestrial*.

Which, finally, brings us to Ernst Chladni and his Chladni figures <7>, or: architectonic structures
appearing in sand due to patterns of acoustic resonance.

Architecture through sound, involving sand. Silicon assuming structure. Desert harddrive, humming.

The gist of Ernst Chladni's experiments involved spreading a thin layer of sand across a vibrating plate,
changing the frequency at which the plate vibrated, and then watching the sand as it shivered round,
forming regular, highly geometric patterns. Those patterns depended upon, and were formed in response to,
whatever vibration frequency it was that Chladni chose.

So you've got sand, dune music, terrestrial vibration, some Chladni figures ? one could be excused for
wondering whether the earth, apparently a kind of carbon-ironic bell made of continental plates and
oceanic resonators, is really a vast Chladni plate, vibrating every little mineral, every pebble, every
grain of sand, perhaps every organic molecule, into complex, three-dimensional, time-persistent patterns
for which we have no standard or even technique of measurement. Or maybe William Blake knew how to do it,
or Pythagoras, or perhaps even Nicola Tesla, but...

The sound dunes continue to boom and shiver. The deserts roar. The continents hum. <8>

(Geoff Manaugh)

+ + + + + + + + + +

<1> http://www.newscientist.com/article.ns?id=dn8014
<2> http://www.cnrs.fr/index.html
<3> For an illustration of the 13 Archimedean solids see
http://www.math.dartmouth.edu/~matc/math5.geometry/unit6/unit6.html, and scroll down.
<4> http://www.newscientist.com/article.ns?id=dn6464; see also
http://news.bbc.co.uk/2/hi/science/nature/3701944.stm
<5> http://www.space.com/scienceastronomy/planetearth/space_symphony_000323.html [Note:
this link offers a contrary, but no less interesting, theory (published in 2000) about
the origins of these planetary soundwaves]
<6> Here I?m referring to the excellent transglobal sonic resource, ShortWaveMusic,
found at http://shortwavemusic.blogspot.com/
<7> For more on Ernst Chladni, click through his Wikipedia entry:
http://en.wikipedia.org/wiki/Ernst_Chladni; and for more on Chladni figures themselves
see http://www.phy.davidson.edu/StuHome/jimn/Java/modes.html
<8> An illustrated version of this post appears on BLDGBLOG:
http://bldgblog.blogspot.com/2005/09/sound-dunes.html




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