sand dunes take lots of low frequency sound, as wind motion of particles, then make huge heaps, then when the huge heaps collapse they make high frequency
This is just a system that makes high quality energy from big amounts of low frequency energy. It is not efficient, although it works.
would
it be possible to make a mathematical model of this to find the optimized shape of particles to cause regular frequent useful energy? Another possibility is applying this to minuscule ocean waves to use even minimal wind velocity to produce energy
so this is another kind of "dust powered engine" that could actually work