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.
various sources