Based on my research on electromagnets, The Fork Organ is an original instrument for live performance. It uses "digital" square waves to precisely drive strong electromagnets at the resonant frequency of nearby tuning forks. When a magnet switches "on" and "off" at juuuust the right frequency, it creates a tiny magnetic field that attracts and releases the steel tines of the tuning fork several hundred times a second, causing it to self-oscillate (and make sound!).