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Listen do you hear that sound. May you may think it's the wind but it's not the sound is coming from these sand dunes. Like a long note from a musical instrument booming sounds like this have been heard in deserts all over the world by ancient travellers in the Sahara by Charles Darwin in the chill land desert. And by this research team from California Institute of Technology may no one fully understands how and why this occurs. But Melanie hunt and Christopher Brennan are seeking an answer here at the Dumont dunes in Death Valley California. This location is one of about 30 places around the world that have what are described as booming doing. The Cal Tech team has been studying this phenomenon for two years now trying to explain the sans ability to produce acoustic energy when disturbed.

One theory stems from the fact that there are a couple of layers to a dune below the top layer of loose sand. There is a harder damper layer the dampness creates surface tension that binds the layers together keeping the force of gravity from causing the loose sand to move down the slope. As the sun beats down the top layer dries out and the cohesion weakens. A bit of wind can set an avalanche of sand into motion. Converting the potential energy of the sand into kinetic energy in the moving sand some of this kinetic energy is then converted into acoustic energy by the sand particles. Better get your God to make the sand dune sing today. The Cal Tech team will hike up to 300 feet and attempt to simulate an avalanche. By sliding down the dune. They will put the loose sand in motion and begin the conversion from potential to kinetic energy.

Guys I got a little bit of a bull a little bit of a bow here or there. The we're going to the diner here ma'am. The team thinks that part of the reason they can create the sound is that the sand in this location has an unusual trait. The sand grains are roughly all the same size so that when they bounce off each other they create the same sound. And we believe that that's part of the explanation for this booming saw that all grains are more or less the same size. So when they flow over one another they hit each other at a roughly the same frequency. The Cal Tech team uses a seismic device called a geophone. To measure the booming

sound. They later feed the data into a computer back at Cal Tech. A. This shows that the song that we were hearing is predominantly a single frequency the frequency that was created at the doing was that of the musical No G. After two years of research and many visits to booming doing sites worldwide the team has identified a few key factors that make a dune sing. It's not only the size of the sand grains that are propelled down the incline via kinetic energy they but also the height of the slope. The change in surface tension and the degree of mobility of the top loose layer of sand compared to the hard packed layer beneath the team at Cal Tech still has quite a bit more documentation to do to confirm their theories. But this creative group hopes to have the mystery solved one day.