Why do some Sahara Desert dunes make booming or singing sounds?

In the Sahara Desert, the phenomenon known as "singing" or "booming" sands occurs when sand is in motion, such as during a footstep or when sand slips downslope. These sounds can range from a musical quality to a deep roar, depending on the velocity and volume of the moving sand.12

For this to occur, the sand must be extremely dry. These specific sands are typically highly spherical and well-sorted by size, which allows them to be highly compact and to shear along thin planes. While the exact cause remains a subject of scientific debate, some geologists suggest the sound is produced by one layer of sand slipping over another. Other hypotheses have been proposed, including theories based on the piezoelectric properties of crystalline quartz, though the mystery has not been fully solved.12