Why Some Dunes "Sing"

Some dry dunes produce a loud, low boom when sand avalanches down a steep slip face. The sand must have particular properties: well-documented singing dunes are made of dry, well-sorted grains. During a slide, grains move in a coordinated way, and collective vibrations create a distinct sound. Different models explain the precise roles of the grains and dune resonance differently, so the mechanism should not be reduced to “grains rubbing together.” At some sites, the boom can last for several minutes.