I was pretty confused when I first heard of singing sand.
But actually, singing beaches are known all around the world! And the sand is singing, squeaking, whistling, or barking when a person scuffs or shuffles his feet with sufficient force on it.
But the best-known place for singing sand are the sand beaches at Basin Head Provincial Park in Manchester-by-the-Sea, Massachusetts. But we count up to 33 singing beaches around the world – in the British Isles, on the eastern tip of Prince Edward Island (Souris), as well as in the fresh waters of Lake Superior and Lake Michigan.
This sand – at Manchester by the Sea – barks like a dog:
What is the source of this sound?
The phenomenon is not completely understood. Quartz sand will sing if grains are very well-rounded and highly spherical. Some believe that the sand grains must be of similar size, close to spherical and have dust-, pollution-, and organic-matter-free surfaces. The “singing” sound is then believed to be produced by shear as each layer of sand grains slides over the layer beneath it.
The sand at Isle of Eigg, Scotland has a weirder sound:
Each patch of sand has its own frequency. Fine sands, where individual grains are barely visible to the naked eye, produce only a poor, weak sounding bark. Medium-sized grains can emit a range of sounds, from a faint squeak or a high-pitched sound, to the best and loudest barks when scuffed enthusiastically.
In this second video at Manchester by the Sea, the sand is not barking but ressembles a sci-fi soundtrack:
Water also influences the effect. Wet sands are usually silent because the grains stick together instead of sliding past each other, but small amounts of water can actually raise the pitch of the sounds produced. The most common part of the beach on which to hear singing sand is the dry upper beach above the normal high tide line, but singing has been reported on the lower beach near the low tide line as well (second video).
Have you ever experimented that weird phenomenon? And what about singing dunes?