~~~~Sound ~~~~Dunes ~~~~~

I'm really beginning to like the BLDG BLOG. Which Rajasthani pink-noiz loving boy wouldn't love these sound dunes?

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.