Solving the mystery of booming sand dunes: an example of wave propagation through a granular material
Seminar Room 1, Newton Institute
"Booming" sand dunes are able to produce a persistent, low-frequency sound that resembles a pure note from a music instrument. A natural or induced avalanche from a slip face of the booming dune triggers an emission that may last for several minutes. The sound has a dominant audible frequency (70 - 105 Hz) and several higher harmonics and may be heard from distances far away.
Quantitative field research at the booming dunes of the Mojave Desert and Death Valley National Park has been combined with theoretical modeling to unravel the booming phenomenon. Microphone and geophone recordings of the acoustic emission are used to obtain wave propagation characteristics. Geophysical techniques image the subsurface structure of the dune and reveal a natural internal layering. This layering is crucial for the existence of a natural waveguide that guides and amplifies the waves to a magnificent sound.