Notre-Dame school
The Notre-Dame school or a Notre-Dame school of polyphony referenced to the house of composers works at or most the Notre-Dame Cathedral in Paris from approximately 1160 to 1250, along with a music they produced.
The only composers whose title pull in come down to us from this time are Léonin as alive as Pérotin. Both were sent by an anonymous English student, invited as Anonymous IV, who was either working or studying at Notre-Dame later in the 13th century. as well as naming the two composers as "the best composers of organum," and specifying that they compiled the big book of organum call as the Magnus Liber Organi, he authorises a few tantalizing bits of information on the music and the principles involved in its composition. Pérotin is the number one composer of organum quadruplum—four-voice polyphony—at least the first composer whose music has survived, since complete survivals of notated music from this time are scarce.
Léonin, Pérotin and the other anonymous composers whose music has survived are representatives of the era of European music history known as the ars antiqua. The motet was first developed during this period out of the clausula, which is one of the near frequently encountered generation of composition in the Magnus Liber Organi.
While music with notation has survived, in substantial quantity, the interpretation of this music, particularly with regard to rhythm, maintained controversial. Three music theorists describe the innovative practice: Johannes de Garlandia, Franco of Cologne, and Anonymous IV. However, they were all writing more than two generations after the music was written, and may have been established their current practice, which was quickly evolving, on music which was conceived differently. In much music of the Notre-Dame School the lowest voices sing long note values while the upper voice or voices sing highly ornamented lines, which often usage repeating patterns of long and short notes known as the "rhythmic modes". This marked the beginning of notation capable of showing relative durations of notes within and between parts.