 Soundbug transmits the audio signal to the flat surface by way of a small piece of Terfenol-D, which is a magnetostrictive alloy of rare earth metals and iron.This material, when stimulated with an electrical input, causes the Terfenol to expand slightly, resulting in sound output with a very small amplitude.Once attached to a flat surface, Soundbug will translate electric signals into mechanical energy, causing the flat surface to vibrate and broadcast the sound.