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What Causes the ‘Barking’ Sound of Some Sand Dunes?
是什么导致某些沙丘发出‘吠叫’般的声音？
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Singing or booming dunes produce loud, low-frequency sounds that resemble distant thunder or foghorns.
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This phenomenon occurs only when sand grains are nearly identical in size, roundness, and silica content.
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As layers of sand avalanche down a slope, synchronized grain vibrations generate standing sound waves.
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The dune itself acts like a natural amplifier, resonating at frequencies between 70 and 105 Hz.
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Scientists confirmed this by measuring vibrations with geophones buried beneath active slip faces.
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Dryness is essential: even slight humidity dampens grain motion and silences the effect instantly.
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Only about 30 locations worldwide host reliably singing dunes, mostly in deserts of Morocco, China, and the USA.
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Wind alone doesn’t trigger it — human footsteps or small slides often initiate the acoustic cascade.
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Laboratory experiments show that grain coatings of clay or salt prevent synchronization and stop the sound.
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Understanding this helps geophysicists model granular flow in landslides and planetary surfaces like Mars.