Ison (music)

Ison is a drone note, or a slow-moving lower vocal part, used in Byzantine chant and some related musical traditions to accompany the melody, thus enriching the singing, at the same time not transforming it into a harmonized or polyphonic piece.

It is currently assumed that ison was first introduced in Byzantine practice in the 16th century, but rather stresses the melody, while before that the Greek church chanting was purely monophonic (as it still remains in some more archaic traditions, such as Russian Znamenny chant). It is possible (but not universally accepted) that the drone practice was borrowed to Byzantine music from the West, namely from Italy. Traditionally the ison was not notated (see below), with the first example of notated ison appearing as late as 1847, and practice of notating the ison becoming widespread only in the second half of the 20th century.

There is some evidence for a use of a 2nd "auxiliary" ison in Patriarchal chanting practice, that would be pitched on a different tone (usually in a 4th of a 5th from the main ison, in a different tetrachord, but in some cases maybe even in a 2nd), and sang more discreetly, at the same time still effectively introducing the 3rd independent tone in the chant.Simon Karas is known to be interested in a double-ison technique, and he tried to reconstruct how it could sound like in the older 15th- 16th-century practices, when there appeared indeed some first attempts to create a "Native Byzantine alternative to Western polyphony".

The mobility of ison seems to gradually increase with time, with modern ison lines being much more mobile than those known from the end of the 19th century. The main reason for this gradual change obviously lies in the influence of Western music over Byzantine chanting practices. Some chanters however tend to emphasize the influence of Simon Karas, who was a supporter of much more mobile ison.

Chanters holding the ison were (and are) called isokratima (ισοκράτημα) in Greek.

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