Three tempora constitute a perfection - akin to a measure of three beatsДЄs in the rhythmic modes, a long may last two or three tempora, and a breve is normally one tempus but can last two tempora if needed to fill a perfection. Like rhythmic modes, Franconian notation is based on ternary groupings on the basic unit, the tempus (now normally transcribed as a quarter note rather than an 8th, as is customary for Notre Dame polyphony Only the organal voices are notatedД¬omposer and theorist Franco of Cologne codified the new system now called Franconian notation in his Ars cantus censurabilis (The Art of Measurable Music) written around 1280.ДЇor the first time, relative durations were signified by note shapes, a characteristic of Western notation. Largest source: Winchester Troper - manuscript of tropes and other liturgical music which contains 174 organa. The styles of organum in Musica enchiriadis were ways for singers to adorn chant in performance based on strict rules for deriving added voices from the chant.ДЄrezzo also described organum in Micrologus Mixed parallel and oblique organum - early form of organum that combines parallel motion with oblique motion (in which the organal voice remains on the same note while the principal voice moves) to avoid tritones

Organal voice - moving in exact parallel motion a fifth belowДЇourths were acceptable but the tritone had to be avoided - this was done by having one voice remain on one note while they could proceed in parallel fourths Parallel organum - voices moving in fifths Organum - term used in treatises to describe two or more voices singing different notes in agreeable combinations according to given rules drones typically sustain the modal final, sometimes joined by the fifth above.ДЇor listeners, drones grounded the melody in its tonal center and heighten the sense of closure when the melody cadences on the final singing or playing a memlody against a drone

Snappy snare drum ornament