Our thanks to Mr Joseph Ahmad, who works as a researcher at the École Biblique et Archéologique Française in Jerusalem, for sharing with us this very interesting article on the use of the “ison” or drone in Gregorian chant.
The subject of this piece is neither homiletics nor ill-timed bee-keeping, but rather some practical notes on how to support a line of plainchant with a drone or ison. Adding a drone is simple—in Byzantine choirs, the task is given to novice choristers—yet it has a powerful effect. When done properly, it fills out the chant’s aural space, enhancing and magnifying its melodic line, modality, and mystagogic aspects.
While the ison is best known today in the Byzantine tradition, being used in both Greek chant and certain forms of Slavonic chant, a number of performers of early music have employed it when singing Latin plainchant since at least the 1980s.
Although some have doubted the authenticity of using an ison with Gregorian chant, there are some oblique references to the practice in Guido d’Arezzo’s 10th century Micrologus (capp. 18-19), and the ison is clearly described in the 13th century treatise Summa Musice (cap. 24). In the section on polyphony, the author states,
“Diaphonia est modus canendi duobus modis, et dividitur in basilicam et organicam. Basilica est canendi duobus modis melodia ita quod unus teneat continue notam unam que est quasi basis cantus alterius concinentis. ~ Diphony is the method for singing two lines in harmony, and it is divided into royal and organic (i.e., organum) . Royal diphony consists of singing in two lines in such a way that one singer holds a single note continuously which is, as it were, the foundation for the chant of the other singer.”
As Marcel Pérès notes [1], the adjective basilica, “royal,” in liturgical matters often refers to the city of Rome. Indeed, in official Byzantine documents—such as the canons and minutes of ecumenical councils—the city of Rome is very often called “Royal and Ancient Rome.” If that is the case here, then the name diaphonia basilica may imply that the practice is originally Roman.
To this we can add some circumstantial evidence. Pairing a drone with a melodic line is by no means a novelty in the world of Mediterranean music. Double-pipes, for example, are as old as ancient Sumer and Egypt [2]; they were widely used in antiquity; they remained popular into the Middle Ages; and their use persists today in the Egyptian arghoul and the Sardinian launeddas. More apropos, the hurdy-gurdy’s larger predecessor, the organistrum, is said to have been used to accompany singing in churches and monasteries: this would make sense given its size and volume, but I’ve not yet found hard evidence for this claim apart from a purported note by Odo of Cluny on how to make the instrument.
Returning to the music, then, the basic drones are as follows:
Mode Drone Flectus
I Re Do
II Re Do
III Do or Mi Re
IV Do or Mi Re
V Fa
VI Fa or Do
VII Sol Fa
VIII Do
Apart from modes III and IV, the placement of the drone is usually straightforward. Depending on the mode, one either holds a single note throughout the chant, or one drones on two notes (the drone and the flectus), changing according to the tonal center of a given phrase—if the drone and the chant are separated by an octave, however, one could probably remove movement altogether. For example, in mode I, when a phrase is centered on La (and above) you will most likely drone on Re; when a phrase is centered on Sol (and below) you will most likely drone on Do, returning to unison on Re at the completion of the phrase. Likewise, you should switch to Do to anticipate a cadence ending on Do or Mi.
The best way to understand this, of course, is to try it out and adjust to what sounds right. Here are some examples to help you get started. The drone is marked by red neumes.
While the ison is best known today in the Byzantine tradition, being used in both Greek chant and certain forms of Slavonic chant, a number of performers of early music have employed it when singing Latin plainchant since at least the 1980s.
The Graduel Si ambulem, sung by the Les Chantres de Thoronet. For other examples, see Columba Aspexit performed by Gothic Voices, Quasi modo geniti by Jerycho, and Kyrie IV by Ensemble Organum.)
Although some have doubted the authenticity of using an ison with Gregorian chant, there are some oblique references to the practice in Guido d’Arezzo’s 10th century Micrologus (capp. 18-19), and the ison is clearly described in the 13th century treatise Summa Musice (cap. 24). In the section on polyphony, the author states,
“Diaphonia est modus canendi duobus modis, et dividitur in basilicam et organicam. Basilica est canendi duobus modis melodia ita quod unus teneat continue notam unam que est quasi basis cantus alterius concinentis. ~ Diphony is the method for singing two lines in harmony, and it is divided into royal and organic (i.e., organum) . Royal diphony consists of singing in two lines in such a way that one singer holds a single note continuously which is, as it were, the foundation for the chant of the other singer.”
As Marcel Pérès notes [1], the adjective basilica, “royal,” in liturgical matters often refers to the city of Rome. Indeed, in official Byzantine documents—such as the canons and minutes of ecumenical councils—the city of Rome is very often called “Royal and Ancient Rome.” If that is the case here, then the name diaphonia basilica may imply that the practice is originally Roman.
To this we can add some circumstantial evidence. Pairing a drone with a melodic line is by no means a novelty in the world of Mediterranean music. Double-pipes, for example, are as old as ancient Sumer and Egypt [2]; they were widely used in antiquity; they remained popular into the Middle Ages; and their use persists today in the Egyptian arghoul and the Sardinian launeddas. More apropos, the hurdy-gurdy’s larger predecessor, the organistrum, is said to have been used to accompany singing in churches and monasteries: this would make sense given its size and volume, but I’ve not yet found hard evidence for this claim apart from a purported note by Odo of Cluny on how to make the instrument.
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| A man playing the double pipe depicted by Simone Martini in the chapel of St Martin, in the lower of basilica of St Francis in Assisi, 1312. |
Mode Drone Flectus
I Re Do
II Re Do
III Do or Mi Re
IV Do or Mi Re
V Fa
VI Fa or Do
VII Sol Fa
VIII Do
Apart from modes III and IV, the placement of the drone is usually straightforward. Depending on the mode, one either holds a single note throughout the chant, or one drones on two notes (the drone and the flectus), changing according to the tonal center of a given phrase—if the drone and the chant are separated by an octave, however, one could probably remove movement altogether. For example, in mode I, when a phrase is centered on La (and above) you will most likely drone on Re; when a phrase is centered on Sol (and below) you will most likely drone on Do, returning to unison on Re at the completion of the phrase. Likewise, you should switch to Do to anticipate a cadence ending on Do or Mi.
The best way to understand this, of course, is to try it out and adjust to what sounds right. Here are some examples to help you get started. The drone is marked by red neumes.
Mode I
Mode II
Mode III
Mode IV
Mode V
Mode VI
Mode VII
Mode VIII
[1] Bernard D. Sherman, Inside Early Music: Conversations with Performers (Oxford UP, 1997): p. 37
[2] See Bo Lawergen, “Extant Silver Pipes from Ur, 2450 BC”. A replica of these pipes is played in this video.
