Jump to content

Welcome to Unexplained Mysteries! Please sign in or create an account to start posting and to access a host of extra features.

- - - - -

Secrets of the Singing Sand Dunes

  • Please log in to reply
1 reply to this topic

#1    __Kratos__



  • Member
  • 25,876 posts
  • Joined:13 Oct 2004
  • Gender:Male
  • Location:Inside the moon

Posted 25 July 2006 - 09:23 PM

The dunes at Sand Mountain in Nevada sing a note of low C, two octaves below middle C. In the desert of Mar de Dunas in Chile, the dunes sing slightly higher, an F, while the sands of Ghord Lahmar in Morocco are higher yet, a G sharp.

Since at least the time of Marco Polo, desert travelers have heard the songs of the dunes, a loud — up to 115 decibels — deep hum that can last several minutes. (You can listen to them here.) While the songs are steady in frequency, the dunes do not have perfect pitch. At Sand Mountain, for example, dunes can sing slightly different notes at different times, from B to C sharp.

Scientists already knew that the sounds were generated by avalanches, but were not sure how. One thought had been that the force of an avalanche could cause an entire dune to resonate like a flute or a violin. But if that were true, dunes of different sizes and shapes should produce a cacophony of notes instead of one characteristic tone.

Now, after five years of research, visiting sand dunes in Morocco, Chile, China and Oman, a team of scientists from the United States, France and Morocco say they have the answer.

In a paper that will appear in Physical Review Letters, the scientists say that collisions between sand grains cause the motions of the grains to become synchronized. The outer layer of the dune vibrates like the cone of a loudspeaker. The particular note depends primarily on the size of the grains.

Indeed, no dune was required at all. The scientists shipped sand from a Moroccan desert to a Paris laboratory and reproduced the singing by pushing the sand around with a metal blade.

“It’s not at all like any other instrument we know,” said one of the scientists, Stéphane Douady of the National Center for Scientific Research in Paris.

The most beautiful dune tune comes from the sands of Oman. “Very pure sound,” Dr. Douady said. “This one is really singing.” The least musical bits of silicon were those from China, which hardly sang at all.

Wow, pretty interesting. If you go to the site and click the 'here' link to listen, it sounds a lot like a ballon being rubbed softly.

"Reality is that which, when you stop believing in it, doesn't go away." ~Philip K. Dick

#2    frogfish



  • Member
  • 11,142 posts
  • Joined:19 Sep 2005
  • Gender:Male
  • Location:The Swamp

  • Flyfishing -- the Art of the Gods

Posted 25 July 2006 - 09:43 PM

That's interesting thumbsup.gif

Posted Image
Researcher-Prostate Cancer Oncogene Research
University of Michigan Comprehensive Cancer Center

The National Center for Biotech Information
My Photo Gallery: Capturing India

Fishing is a Way of Life!

0 user(s) are reading this topic

0 members, 0 guests, 0 anonymous users