A small 5x5 disk magnet is placed on a speaker cone and a plastic cup is positioned on top of the magnet. In the cup there is oat milk, food color and ferrofluid. It's critical that the magnet isn't too strong allowing the ferrofluid to move somewhat freely, also there needs to enough ferrofluid so that it shows on the surface. For this effect to emerge, the amplitude or volume cannot be too high or low, just enough volume that the surface starts have waves. The frequency of 51Hz is generated with online tone generator.
Watch the effect in real time: [ Ссылка ]
