Sand dunes can sing, and they do it loudly!
Imagine travelling across wide empty desert dunes when suddenly a loud low-pitch rumble, a roar, fills the air. How would you explain it? Early explorer Marco Polo suspected evil spirits were at play. Charles Darwin stated that he could not explain it. I haven’t yet experienced singing sand myself but next time at a san dune I’ll follow the expert instructions with hope.
Photo: David Gavi
If the conditions are right desert dunes can sing or hum. It sounds like the lower notes on a cello played again and again. Others describe it as “dozens of drums played at the same time”. You can hear the natural sound phenomenon up to 10 km/6 miles away.
Dunes at different locations sing different tones
Researchers recording dunes found that a Moroccan dune sang a low G-sharp, while an Omani dune let out nine different tones. Looking at grain size the Moroccan grains were similar in size and shape, while the Omani sands differed. Drier sand grains gave a deeper sound than damp ones.
Scientists still investigate and debate the exact science of how dunes sing. It seems that the tune depends on grain size, shape and temperature. The squeak that some sand makes when walking on it is something else. I’ll save that for another post.
Singing sand dunes are rare, there’s only about 40 sites worldwide. Agreed is that sand avalanching, set off by wind or by someone walking near the top of the dune, sets off the sound. The loud noise is the sound of sand grains bumping into each other. The human ear can not detect one single sand grain bumping into another. But a billion grains colliding together will roar. Strength in numbers!
If you’re close to a dune and you want to hear it sing do as the researchers: 1. Climb up to the top of a dune on a dry day.
2. Once at the top sit down and spread your legs wide, as if stretching after exercising.
3. Start scooting down trying to create a small sand avalaunch.
Your best chance is at a dune well known for singing but who knows, you might find an unknown singing site. If you don’t – you can always pick a favourite song and sing yourself!