In his theoretical tonary "Musica disciplina" Aurelian of Réôme asked a Greek about the meaning of the syllables, and reported that they had no meaning, they were rather an expression of joy as used by peasants to communicate with their working animals like horses.
The music contained in the troper was long considered to be indecipherable, as there are only rudimentary indications of pitch and duration by the use of a form of notation known as neumes and a tonary which classified and indicated the melodic mode (octoechos).