Dunesong is something we worked on with a group from UC Santa Cruz
for about 7 years in the 90s as part of a team headed by the late Ken
Norris (the fellow who discovered how dolphins echolocate and who was
head of the Environmental Studies Dept, there). The team consisted of
a nuclear physicist, several geologists, two naturalists, and a
storyteller (for our evening campsites).
Studies of dunesong were first initiated by Bagnole in the mid-50s
and have been going on ever since, however intermittently. There are
several literary references to dunesong in T. E. Lawrence's (Lawrence
of Arabia) writings. Native Americans of the southwest have ancient
myths that tell of the spirits hiding in the desert that speak to
them at certain times and sites. Dunesong, because it is very low
frequency, can often be heard 7 - 8 miles (11 - 13km) from the point
of origin if the weather conditions are right.
We measured 10 different sites in the West and Southwest (Nevada,
California, Arizona, N. Mexico and Colorado). No one knows for sure
what's happening since not all dunes "sing" and those that do, do not
do it all the time. After measuring sand grain size, shape, angle of
repose (of the slipface of the dune), surface and depth temperatures,
accumulated moisture at different layers, and magnetite content, we
figured that when certain grain size, shape, and magnetite and
moisture create ideal conditions for dunes to "sing," they begin to
resonate. Sometimes they "tire" and have to recharge before "singing"
again.
Typically, when conditions are right, a drier layer moves slowly over
a more humid layer, which, in turn is moving at a slightly faster
rate than the one below it. Each layer forms ridges as it moves
downward. No one knows for sure if the movement (friction) over the
ridges (wave forms of a physical type) causes resonance. But some of
us think it does assuming all other conditions conspire.
Two ways dunesong can be introduced: (1) naturally, when the angle of
repose and other conditions are just right and assuming the dune is a
"singer," and (2) by climbing all the way up to the top of the dune
ridge and sliding down on your ass. Dunesong sounds more like a
freight train to me - having none of the hi-freq of a jet - and can
last anywhere from a few seconds to over three minutes. They range
from infrasound (in the 5Hz range) to around 120Hz and each dune
seems to have it's own range of signatures unique to that site.
I've got a good example of Kelso singing if someone will walk me thru
the process of how to post it.
Bernie Krause
> >To the north about 10 miles are the Kelso Dunes, one of the
>>sites in the desert SW where you can record the dunes singing
>>assuming conditions are right and you have the right transducers (a
>>pair of good PZM mics or hydrophones in ziploc bags of water buried
>>in the sand in order to get the infrasound component at around 10Hz).
>>Best window to record is between late March and May. There's also a
>>National Park Service visitor center north of the dunes on the
>>Kelbaker Rd at Kelso where we've just installed a couple of
>>soundscapes representing the desert in that area. It is scheduled to
>>be open sometime in August of this year.
>
>I visited the Kelso Dunes on my way back from recording at Joshua
>Tree National Park a couple of weeks ago. I climbed most of the way
>up the big dune, but they weren't sayin' anything. What are the
>conditions that produce singing?
>
>BTW the interpretive sign said it sounded like an airplane. I heard
>several of those, but I wasn't fooled.
>
>-Dan Dugan
>
>
>"Microphones are not ears,
>Loudspeakers are not birds,
>A listening room is not nature."
>Klas Strandberg
>Yahoo! Groups Links
>
>
>
>
--
Wild Sanctuary
P. O. Box 536
Glen Ellen, CA 95442
t. 707-996-6677
f. 707-996-0280
http://www.wildsanctuary.com
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