This is purely conceptual and I'm just looking for opinions on whether its misguided or, indeed, plausible. From what I understand about Fourier decomposition we can break down an analog signal into component sinusoidal waves. My thinking is that the sound system at a nightclub can be considered such an analog signal, and we can crudely/roughly get a decomposition of the activity of various wavelengths by watching excitations in the surface of water placed in glasses of varying diameter. To demonstrate this I would just line up say, a shot class, a tumbler glass, a highball glass, and a martini glass each filled with water, or alternatively several glass shakers each filled with water to a different level, and point out how each one vibrates at different points to the music which corresponds to the different frequencies. Would this be a correct interpretation of the phenomenon? Likely in actuality the heavy bass would just make them vibrate all at once, but hey, I'm a bartender, not a physicist.