Dune tunes.

Trek through the dunes of Sand Mountain, Nevada, and you might hear eerie "music." No, it's not an off-key Elvis impersonator from distant Las Vegas. When wind blows on nearly 100 desert dunes around the world, the sand emits a long, loud, booming noise.

How is this possible? For years, scientists didn't have the grain of an idea. But a team of Canadian researchers may be on their way to solving the mystery. Marcel Leach and Douglas Goldsack knew that "singing sand" grains have super-smooth surfaces. But they discovered the grains are also coated with a thin layer of silica gel, a pearly, slightly sticky mineral. Regular desert sand doesn't have this coating, or this noise.

To find out if silica gel is the "voice," the scientists filled a jar with artificial sand made of tiny silica gel spheres. When they shook the jar, the spheres made a humming sound. What gives? "We know what may be producing the sound," says Leach. "Now we have to figure out for sure how the particles do this."

One hypothesis is that silica gel makes sand grains stick together. When wind blows the sand, the grains shake in unison, producing a simultaneous vibration. And that's what sound is: vibrations traveling through air. (Touch your throat as you talk and you'll see what we mean.) Even Elvis would be impressed.