"Singing Sand Dunes Explained"

Photograph by Frans Lanting, National Geographic

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Written By:

Shannon Fischer

for National Geographic News

Published October 31, 2012

Sand dunes have been known for the "songs" they would sing but the average person may not exactly know how they can. First of all, as sand grains shuffle down the slopes of certain sand dunes, they produce a deep, groaning hum that reverberates for as far as miles. 

Different dunes sing different tunes and some even sing more than one note at a time. A trio of Parisian biophysicists suspect that this is due to the size of the grains, although reasons still remain unknown to this day. These researchers first located a pair of singing dunes, in in Morocco and the other in Oman. After triggering avalanches, they found that, while the Moroccan hill moaned at a steady 105 Hz—or a low G sharp—the Omani dunes sang a nine-note blare that ranged from 90 to 150 Hz (for those musically proficient).

The Parisian group speculates that, during an avalanche, grains of sand move together down the dune with each grain colliding and rolling around its neighbors, creating a continuous stream of collisions. "Each bump makes a shock that, on its own, would be all but inaudible. But add them together in the right conditions, said study co-author Stéphane Douady—and the team is still working out what those precise conditions actually are—and you get 'the sound of millions of little shocks'" (Fischer).

I personally have never visited sand dunes but after watching videos of what they offer musically, my interest grew. It's fairly difficult to imagine rocks (even small grains) to make pitches through collisions, but there are many aspects of physics that are yet to be introduced to me, or to be discovered for everyone to observe.

- Andrew