Organum is a genre of Medieval polyphonic music (music with two or more simultaneous, different voice parts) that reached the peak of its sophistication during the late 1100s-early 1200s in France. In organum, new music would be composed and sometimes improvised on top of the “fixed” music of older Gregorian chant.
At first there were just two parts — one for the chant and the other to provide harmony or, in later music, to provide a faster, melodic part that decorated the chant. As more voices were added and the rhythmic and harmony behind the music became more sophisticated, it evolved into new musical forms such as the motet.
What to listen for:
- In organum, the chant is always in the “tenor” voice (this is different from the kind of singer—“tenor” is a Medieval term referring to the lowest voice part, basically, and could actually be an alto or bass singer).
- A notable feature of most forms of organum is that the tenor voice is usually singing very long notes (the chant has been stretched out in time) while the upper voice(s) are singing much faster music, creating a sense of two different tempos happening simultaneously.
- Like the chant on which it is based, organum is derived from a modal pitch system rather than the tonal system.
- Alleluia: Angelus domini (2) oblique organum [YouTube]
- Alleluia: Angelus domini (3) Free Organum [YouTube]
- Viderunt omnes, Perotin [YouTube] from 1198. This is one of my personal favorite pieces of Medieval music.