As I said previous with different words. Some people sell stuff, and they don't know how it works. Is that science or just luck. Mahgister and I are grasping straws, but we know how and why they work so we put them to great use as we do with minerals and metals of various shapes suspended from a ceiling or placed on a flat surface or attached to a wall. The compressive we hear is the result of the shear velocity in solids and their shapes.
My suggestion is for the listener to study up on shear wave polarity and their velocity as well as laminar flow. With some application and experimenting there is much to be learned and gained in the field of wave transmission. Tom
Tom