Singing Sand is a natural phenomenon of sand. Under the influence of wind, the shearing and compression of sand grains can produce various types of noises. There are two distinct types of singing sands:

• A "Squeaking" or "Whistling" sand, which is most often found at beaches, shores and riverbeds. This sound is a short high frequency (500-2500 Hz) sound. This sound is generated by sand that has recently been exposed to water, and dried. It is unclear whether the sound is generated from a reordering of the sand structure, or from the washing away of impurities. This type of singing sand is common, but does not extend inland for more than 30 m away from the shore. Squeaking sound is also emitted from sand that is totally submersed, under the influence of tidal or wave motion.
• A "Booming" Sand. This type is found in large isolated dunes in deserts, and is more rare. It is a loud, low frequency (50-300 Hz) booming sound that can carry as far as 10 km. Observers have described this sound as the sound of a tuba, hums, moans, drums or thunder. This effect occurs only when the sand grains are very dry.

Important factors for the occurence and tone of singing sands are the average grain size of the sand (and its particle size distribution), its shape, and surface morphology.

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There are dozens of singing beaches in the world. The most famous site is Camas Sgiotaig on the Isle of Eigg in western Scotland. Most of the sites produce the "squeaking" type of sound... on Eigg it's because the sand is actually made up of tiny granules of rounded quartz. It's a watery little mousy noise, very short in duration.

More impressive is booming sand. I'm not so sure I believe the "10 km" figure, but the sound is amazing. It's a powerful, lengthy hum, and sounds almost exactly like the buzzing tone at the beginning of Korn's Follow the Leader LP. The sounds seem to capture the majesty of the giant dunes on which they are found.

Singing sands lose their ability to sing with pollution -- entire beaches in Japan and Brazil have lost their song. Even a minute bit of flour has halted the signing of Eigg's sand in laboratory tests. The science of the vibration depends on the sand's purity. So, if you ever discover a singing stretch of beach, it's probably not a good idea to celebrate your find by throwing a wild kegger on the site.