"He's helping me win a bet"

Those amongst you who've read Cryptonomicon will appreciate the following from We Make Money Not Art:

TEMPEST is based on the surveillance technology known as Van Eck Phreaking - computer screen content can be reconstructed remotely by picking up the emitted EM-field of the screen.

TEMPEST utilizes this technique to transform purely generative graphic into a composition of noise which again is fed back into the image generating process. Several AM receivers are tuned into different frequencies of a screen and plugged into an audio mixer for further sound processing. The graphics on the screen become a means of producing sound and it is only the graphics which determine the different timbres and rhythms.

By Erich Berger.