Kan ha diskan is probably the most common type of traditional music of Brittany.
It is a vocal tradition (kan ha diskan translates from Breton as, roughly, call and response singing).
Kan ha diskan can be songs about any subject, but must meet one of a number of a meters used in folk dances, mostly line or round.
In addition to the Goadecs, the singer Loeiz Ropars largely responsible for maintaining kan ha diskan's vitality in the middle of the 20th century, and the 1960s and 1970s revivalists drew largely on his work.
During the folk revival, aspiring musicians sought out elder teachers to learn kan ha diskan from, generally being viewed as successful when the student can act as diskaner to his mentor.