It’s a fascinating area. Those drops usually stimulate the brain’s reward circuitry by releasing dopamine and by entraining neural oscillations that sync with the body’s rhythms. When the frequency of stimulation matches natural brainwave patterns—say the gamma or theta range—it can amplify perception of pleasure. I’d start by looking at how specific sound frequencies modulate the dopaminergic pathways and then see what neuroimaging data say about changes in activity across the mesolimbic system. If you want to dig deeper, let me know what data you’ve got, and we can design a controlled experiment.