As for how it works, its EM not acoustic.
I think it is the 2, the EM field modify the acoustical setting of the room and not only the physiology of perception...But your remark about the brain waves and the range of resonance of the S.G. seems very truthful to me and a relatively recognized fact...But it is not only like i said that the S.G. are affecting the human physiology but the room acoustic also because if you put on the S. G. a shungite plate or a quartz the effect are very different....And these changes are not pick by the brain directly but through the acoustical changed properties of the room....Then the S. G. change the physiology of perception but the acoustical space also....
Keep in mind that mine work in an interconneted grid with very thin copper cable, connected also to a varied grid of resonators of different size and different materials on the main caps, these materials (shungite and quartz or tourmaline) modify the audible effect in opposite direction, for example, amongst other effects, compressive or decompressive action with a positive or a negative impact...Balancing shungite and quartz gives the best timbre perception....
the modified and interconnected S.G. then does not change only imaging and soundstage but also timbre perception.... And timbre is not undertood in term only of pure frequencies but with other factors linked to the acoustical setttings of the room ( the spectral enveloppe but also the time enveloppe)....
The general impact of my grids is so great that there is absolutely no relation between my audio system S.Q. before and after....