The study of the Armenian system of notation called Khazs (Neumes) is of significance both for Armenian and Byzantine music from a historical and aesthetic point of view. Over the centuries the Armenian people have created a musical culture which is largely inaccessible because of the fact that to this day the medieval notation of this music has not been deciphered. Prof. R.A. At'ayan's unique study based on the abundant manuscript sources of the Institute of Ancient Manuscripts (Erevan) not only traces the origin and development of this notation system convincingly, but also re-creates the tunes of the numerous chants and songs composed over the centuries.