Click on the image to enlarge

The mysterious sounds of desert sand dunes have long fascinated, at least since the days of Marco Polo, one of the first explorers who have identified this phenomenon. Marco Polo however, did not scientifically analyzed it, but thought these sounds came from evil spirits ... In reality, it is a physical phenomenon that has an explanation (or even more then one explanation).

What is the Song of Dunes?

Singing sand dunes is a natural phenomenon. It can emit sound like, according to its frequency sound, a woodwind instrument or a plane! Sands from Dunes found in deserts of China and the U.S. have issued, according to observers, a frequency of 110 decibels, which is still tolerable for the human ear but almost deafening!
The most impressive sound is emitted when an avalanche is triggered on the steeper side of the dune and lasts until the avalanche reaches the foot. Most surprising to scientists is that the sounds have a certain harmony.

How the phenomenon occurs

The assumption of most scientists is that during an avalanche, the sand grains move in a synchronized manner. This synchronous movement of sand grains in a quiet environment produces a tuba feature alike. Or, some say, a sound similar to those issued by Buddhist monks meditating!
A French scientist, Stephane Douady, who retains the assumption of synchronous movement of sand grains to explain the dune symphony, has experienced the phenomenon in the Western Sahara region of Morocco. 

See also the movie below: