"Chijikinkutsu" by Nelo Akamatsu

This piece from 2013 won the Ars Electronica prize 2015 in the category of "Digital Musics & Sound Art". It illustrates geomagnetism: terrestrial magnetic properties that cannot be sensed by the human body but that exist everywhere on earth.

An iPad sends MIDI signals to each electromagnet, as explained on the project website.