Singing Sand

From ‘Travels in Arabia Deserta’ by Charles M. Doughty

In the Nefud, toward El-Hyza, are certain booming sand hills ... such as the sand drift of J. Nagus, by the sea village of Tor, in Sinai: the upper sand sliding down under the foot of the passenger, there arises, of the infinite fretting grains, such a giddy loud swelling sound, as when your wetted finger is drawn about the lip of a glass of water, and like that swooning din after the chime of a great bell — or cup of metal — Nagus is the name of the sounding board in the Greek monastery, whereupon as the sacristan plays with his hammer, the timber yields a pleasant musical note, which calls forth the formal colieros to their prayers; another such singing sand drift, el-Howayriah, is in the cliffs (east of the Mezham) of Medain Salih.

Listen to some amazing recordings here.

HUMS

from Wired:

You can’t hear it, but the Earth is constantly humming. And some parts of the world sing louder than others.

After discovering the mysterious low-frequency buzz in 1998, scientists figured out that the Earth’s hum is caused not by earthquakes or atmospheric turbulence, but by ocean waves colliding with the seafloor. Now, researchers have pinpointed the source of the Earth’s “background noise,” and it looks like it’s coming primarily from the Pacific coast of North America.

When two waves of opposite direction but similar frequency collide, they create a special kind of pressure wave that carries energy to the ocean bottom. As these waves pound against the sea floor, they generate a constant vibration with a frequency of about 10 millihertz, much too low for humans to hear but easily detectable with seismometers. By comparing the intensity of the hum with the height of waves around the world, scientists can track where the buzz is coming from.

Previous studies suggested that waves from both shallow continental shelves and the deep ocean contribute to the Earth’s hum, but new data indicates otherwise. Based on measurements from a seismic observatory called the USArray EarthScope, most of the hum appears to originate from the Pacific coast of North America, with a smaller contribution from the west coast of Europe. Waves from the deep ocean don’t seem to make much hum at all.

Listen to a version sped up enough for human ears. Courtesy of UC Berkeley Seismological Laboratory.

There are other unexplained HUMS around the globe that are audible to the human ear as well. The Taos (New Mexico) Hum is well known amongst many residents, but the Auckland Hum from the North shore of NZ is well documented and more importantly well recorded. Listen to this uncompressed wav file. And another. - sounds from T.J. Moir