A new magnetic fluid device is developed in which the magnetic fluid is manipulated in synchronization with sound. The magnetic fluid moves due to changes in a magnetic field produced by several electromagnets installed above and below a shallow, horizontal acrylic panel in which the magnetic fluid is held. The voltage to each electromagnet is controlled according to sound input by computer processing, making the fluid pulsate like a living thing.

you can find more information on:

http://www.kodama.hc.uec.ac.jp/project/protrude.html