Sand on a dune possesses energy in the form of gravitational potential energy. The greater the height of the sand dune, the more gravitational potential energy the sand on top has. When the sand on top of a steep dune is disturbed, it slides down the slope, and gravitational potential energy is transformed into kinetic energy. It is this kinetic energy of the falling sand that produces the booming sound. As the sand particles bounce against each other, some of their kinetic energy is transformed into acoustic energy -- or sound, waves of vibrations transmitted through a medium.
