ORGANUM: General name for polyphony from about the 10th century to about the 13th

In Organum, a preexistent chant is embellished by the addition of other voices singing different music. When music is made up of people singing or playing different lines at the same time, it is said to be polyphonic.

Stages in the Development of Organum

1. Parallel Organum (9th-10th Century): Added voice moves in parallel fourths and fifth either above or below the chant. Examples come from treatises.

2. Free Organum (10th and 11th Centuries): Added voice moves note-against-note using a variety of intervals. The chant is in the bottom voice.

    1. Melismatic Organum (11th and 12th Centuries): Added voice has melismas sung over held notes in the lower voice (which still presents the chant).



Notre Dame Organum sets the solo sections of the responsorial chants of the Mass and Office. The organum is highly melismatic; can be for 2, 3, or 4 voices; chant is always in the lowest voice called the Tenor. Long held notes in the Tenor except for places where a melisma appears in the chant (see Clausula below).


I. Types of Notre Dame Organum

    1. Organum purum, also called Organum duplum: Tenor plus one added voice called the duplum; added voice may be organized rhythmically, but nobody is quite sure,. and the most recent opinion is that it isn't. Léonin is said to have composed a cycle of Organum purum settings of the soloistic sections of the responsorial chants of the Mass and Office for the liturgical year: this is called the Magnus Liber.
    2. Organum triplum: 3 voices: Tenor plus two added voices above called duplum and triplum (triplum is the highest voice). Rhythmic notation in the added voices. Pérotin is said to have composed some organum triplum settings.
    3. Organum quadruplum: 4 voices: Tenor plus three added voices called duplum, triplum, and quadruplum (quadruplum is highest voice). Rhythmic notation in the added voices. Pérotin is credited with organum quadruplum settings such as Sederunt (Anthology, p.64).

II. Special subcategory of Notre Dame Organum

Clausula: May appear in any Organum setting. Corresponds to a melisma in the underlying chant melody. The Tenor and upper voice/s are clearly organized rhythmically. This is called Discant Style to differentiate it from the melismatic style of Organum proper. Originally part of organum settings, the clausula soon begins a life of its own as a separate genre. It is always characterized by being based on a snippet of chant which is organized in rhythmic cells above which rhythmic voices are placed. There is no text except the syllable/s of the original melisma that generated the first clausula setting of any chant excerpt.


III. The Notre Dame composers also produced a special genre called the Conductus.

The conductus is not based on chant. It has newly written text and music and may be for 1 to 4 voices. All the voices sing the same text and generally move in a note-against-note style (i.e. the Tenor does not have long held notes as in Organum). The texts could be religious or could refer to contemporary events.