Tag: outdoors

Booming Sand Dunes

Singing sand dunes can create loud drones during avalanches.

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(Your tablet ot computer loudspeakers may fail to reproduce this low frequency sound).

Some sand dunes make a strange low frequency humming sound a bit like the drone of a distant propeller aircraft. The sound can be surprisingly loud: in some cases it can be heard many kilometres away. This is something that has been known about for centuries: Marco Polo, the Emporer Baber and Charles Darwin all wrote about it [1]. For instance, Marco Polo wrote about his encounter in the Gobi Desert “[the singing sands] at times fill the air with the sounds of all kinds of musical instruments, and also of drums and the clash of arms.”

The sound is rather unusual and eerie – reminiscent of a bass musical instrument. The drone is caused by a synchronised avalanche of the sand grains. The pitch of the note produced depends on the size of the grains – and so each singing sand dune has its own distinctive voice pitch. But the exact reason for the grain synchronisation is still being argued about among scientists.

Logistics

Consider safety as you’ll be visiting a desert in the height of summer. About thirty dunes around the World boom. The large dunes most reliably sing in the summer when the grains are dry. Small dunes tend not to sing. As the videos show, you can start the avalanche yourself: once the sound has started it can continue for sometime after you stop pushing the sand. Do this on the leeward face of the dune (the side sheltered from the wind). The dune needs to be steeper than about 30 degrees.

Below is a list of locations gleaned from the Internet – it would be wise to check with locals about the exact locations.

  • Atlantic Sahara desert around Laayoune, Ghord Lahmar dune near Foum Agoutir, Morocco [2]. (Also Erg Ezzahar or screaming dunes)
  • Kelso Dunes near California’s Mojave Desert, off the Kelbaker Rd, north of Highway 40 between Barstow and Needles, Ca, USA [3]
  • Kelso, Sand Mountain (20-21 miles east of Fallon, Nevada on Highway 50, USA [3]
  • Crescent Dunes (about 15 miles west of Tonopah, Nevada, USA [3]
  • Dumont Dunes (60 miles north of Kelso, Ca, USA [3]
  • Big Dune (Amaragosa Valley, south of Beatty, Nevada, USA [3]
  • Eureka Dunes (Hanging Rock Rd, out of Bishop, Ca, USA [3]
  • 40 km southwest of Doha, Qatar
  • La Mar de Dunas and El Cerro Bramador, Copiapo, Chile
  • The Dune of Altynemel (“The Singing Dune”) in the valley of Ili River near Kapchagay, Kazakhstan
  • Near Liwa, South of the United Arab Emirates. In area known as the Empty Quarter
  • Dunes of Badain Jarin, Inner Mongolia, China
  • Dune Ming Sha Shan, The Mount of Singing Sand, DunHuang, Gansu, China

Credits

  1. http://www.its.caltech.edu/~nmvriend/research/
  2. http://www.pmmh.espci.fr/fr/morphodynamique/SongOfDunes.html
  3. Wild soundscapes: discovering the voice of the natural world, Bernard L. Krause, Wilderness Press
  4. Sound (c) Nathalie Vriend

Golkonda, India

Guides will demonstrate the clapping telephone, which was used to signal over long distances in this ancient city.

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This is the ruined city of the Kingdom of Golkonda (c. 1364–1512) which has several curious acoustic features including what has been described as an “amazing clapping telephone”. Clap near the entrance, and sound is reflected by a nearby building so that it can be heard a kilometer away at the highest point of the city, at the Bala Hisar pavilion. Some other quirk of this “magical acoustic system” means that close to the person clapping, the sound can only be heard within a few metres.

Demonstrating the clapping telephone. Lynn Robert Carter commented that the sound is more remarkable than appears on this video.
There’s also an interesting flutter echo as well

Logistics

11 km west of the city of Hyderabad, Andhra Pradesh state, south-central India. Suggested website for more information.

Credits

  1. Photo: mikecogh (c) some rights reserved

Animated Clock

Watch and listen to the animated town clock at this UNESCO World Heritage site

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Goslar is a medieval masterpiece: narrow cobbled streets, canals and picturesque houses are some of attractions. Indeed, the whole city is a UNESCO World Heritage site. But for the sound tourist, it’s the old animated clock in the main square which is the must-see attraction. A procession of mechanical figures slowly troop out of the clock innards to re-enact the town’s history; celebrating its prosperous mining past.

Logistics and location

Situated in Goslar’s Marktplatz. Sounds at 9am, 12, 3pm and 6pm.

Sources and credits

  1. Photo: Gerhard Elsner (c) some rights reserved

El Castillo, Chichen Itza

The echo from the staircase disorts the sound, creating a chirp like a bird, maybe even the sacred quetzal bird.

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Listen to the distorted echoes immediately after each handclap: they sound rather like a chirping bird.

The Kukulkan Pyramid in Chichen-Itza, known as “El Castillo” (the castle), is one of the seven new wonders of the world. It’s arguably the most spectacular and most frequently visited Mayan site in Mexico. If you stand at the bottom of the steps and clap your hands you get this incredible chirping sound.

Whether the pyramid was constructed to deliberately make this noise or it happened by chance is still a matter of debate among archaeologists. Reflections from the treads of the staircase are responsible for the echo being altered. The reason that a chirp like a bird is produced is because of geometry. The time between later reflections is longer than early reflections, causing the frequency of the echo to rapidly drop by about an octave.[2]

There is another sound effect here, but unfortunately as people are no longer allowed to climb the steps it’s hard to experience. Apparently, if you sit at the bottom of the stairs the sound of footsteps from people above you is like raindrops falling into a water-filled bucket rather than footsteps. The effect is caused by sound skimming the surface of the staircase. The sound reflects off the regular pattern of the stairs, creating a very distinctive effect [3].

Other acoustic phenomena

The Great Ballcourt is a huge semi-enclosed areas. If you clap your hands, the sound repeats a dozen times (this is a flutter echo) [3]. Also a whisper carries a huge distance if you speak from one of the raised areas [4].

Location

Wikipedia page.

Credits

  1. Photo: By Mariordo (Mario Roberto Duran Ortiz) – Own work, CC BY-SA 3.0
  2. David Lubman: http://www.ocasa.org/MayanPyramid.htm
  3. The Acoustic Raindrop Effect at Mexican Pyramids: The Architects’ Homage to the Rain God Chac?, Calleja, JAC; Declercq, NF, ACTA ACUSTICA UNITED WITH ACUSTICA, 95(5) 849-56 (2009)
  4. http://www.luckymojo.com/esoteric/interdisciplinary/architecture/ecclesiastical/mayanacoustics.html
  5. Sound (c) robgodd

Squeakings Sands

A beautiful beach, the wind in the hair, the waves lapping on the shore, the soothing sound of squeaking underfoot!

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The beach at Porthor is known as the Whistling Sands, which in many ways is an odd name because squeaking sands would be more appropriate. As you walk along the beach the sand squeaks underfoot. I experienced a similar phenomena on Whitehaven Beach, Whitsundays, Australia beach and it’s distinctly odd.

One suggestion is that the sound is caused by friction as the grains rub against each other, but this isn’t proven. What is known is that you need the right sort of sand grains: ones that are near spherical with no sharp edges. This is probably why the effect is only heard on some beaches. The squeaking is most audible when the sand has been recently washed, and so it’s rarely heard far from the shoreline. On the beech, the sand needs to be dry (although submerged sand can also sometimes squeak) [2] so check the weather before travelling!

Logistics and some suggested locations

Whistling Sands – Porth Oer, Wales

Owned by the National Trust

Whitehaven Beach, Whitsundays, Australia

Can be reached via ferries and other boats.

Other reported sites

Australia

  1. Pilots beach in Laurieton, NSW
  2. Thistle Cove, Cape Le Grand National Park
  3. Neck Beach, Bruny Island, Tasmania
  4. Moreton Island, Australia
  5. Surfer’s Paradise, Australia
  6. Bondi beach, Australia
  7. Squeaky Beach, 5607, Australia
  8. Wilson’s Prom., Victoria, Australia

USA

  1. Cocoa beach, Florida
  2. Treasure island, Florida
  3. Henderson Beach Destin, Florida
  4. Tybee Island, GA, USA

Cources

  1. Sound Benboncan (c) some rights reserved
  2. Sholtz, P., Bretz, M., and Nori, F. (1997). “Sound-producing sand avalanches,” Contemporary Physics 38, 329-342.
  3. Eifion (c) some rights reserved
  4. map thumbnail.Storm (c) some rights reserved