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Sand dunes play tunes
Posted by Jennifer Spiller on March 01, 2021
People who visit or live near sand dunes have noticed a particular humming phenomenon. It seems as if the dunes are playing music. The question is: why? The sand at the surface of the dunes is much dryer than underneath. As the sand starts to tumble down the sides of the dunes, the sound vibrates through the dry layer and bounces off the moist layer (which is denser), causing a standing wave (where the vibrations going down and coming back up move in sync with each other) and producing sound. If you’re curious, the note that is hummed is often E, two octaves below middle C, although it can vary slightly in pitch depending on the thickness of the dry sand.
