The technological developments of the 20th century have made much of the electromagnetic spectrum visible or audible to humans. The device that has found the most complete integration into our everyday sensual world is the hearing aid. Designed for the hard of hearing, their primary function is simply to amplify environmental sound. However, a lesser-known additional feature of hearing aids is their ability to provide a portal to the world of electromagnetic waves - via the built in telephone coil. This is a broadband receiver of magnetic transmissions which can be relayed into the ear of the wearer. It enables them to listen to induction loops that are provided through specialist telephone and public address systems but also any other electrical currents in the vicinity. Tonic Train propose to co-opt this outdated medical electronic equipment for a performance using 8 modified hearing aids as electromagnetic receivers. The resulting concert will produce an intense feedback-based audio experience.