Singing sand

The sound emission accompanies a slumping or avalanching movement of sand, usually triggered by wind passing over the dune or by someone walking near the crest.

On some beaches around the world, dry sand makes a singing, squeaking, whistling, or screaming sound if a person scuffs or shuffles their feet with sufficient force.

It has also been speculated that thin layers of gas trapped and released between the grains act as "percussive cushions" capable of vibration, and so produce the tones heard.

Fine sands, where individual grains are barely visible to the naked eye, produce only a poor, weak sounding bark.

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.

[5] Singing sand has been reported on 33 beaches in the British Isles,[8] including in the north of Wales and on the little island of Eigg in the Scottish Hebrides.