The Ear of Dionysius is the name given to a cave in Syracuse, Sicily by the painter Caravaggio. The cave possesses amazing acoustical properties that let a person inside the ear whisper to someone at the other end. Upon noting this Caravaggio claimed that the cave was used as a prison which let Dionysius eavesdrop on the conversations inside.

The story is apocryphal, but the acoustics are real. The shape of the Ear focuses sound waves so that whispers in one end can be heard clearly in the other end. Ear of Dionysius has come to generically refer to any such structure.

The Ear of Dionysius proposed for the CNSI is inspired by an idea of film-maker Julian Rohrhuber. Like the one in Syracuse, it facilitates communication at a great distance. But unlike the original, it is not physical, but virtual; and the whispers it captures are digitally transmitted. It will provide anyone, anywhere in the world a chance to manipulate one of the most intimate aspects of a space: its sound.

Far from being a tool for eavesdropping, this Ear of Dionysius will be an instrument of interaction and transparency.