A rare rune seemingly favoured by phonologists and others interested in that field. While its main applications are a mystery it has been shown to have offensive capabilities. In the Dunan Unification War, during the Battle of Greenhill, the phonologist Connell managed to repel a number of Highland Army officers by having his Sound Rune emit a high pitched noise.

Before its uses in Suikoden II, the phonologist Melodye request a sound crystal from Tir McDohl in order to recruit her. After recieving the sound rune Melodye joined the army, hoping to use her Sound Rune in any way she could to aid the war effort.