One aspect of medieval music now receiving much interest is the matter of tuning. This FAQ article is intended to explain the system of tuning in perfect fifths commonly known as "Pythagorean intonation," its interaction with the stylistic traits of medieval polyphony, and its relationship to other systems of tuning.
While our focus here is on the music of medieval Europe, the concept of a tuning based on a series of twelve notes in perfect fifths also plays an important part in other world musical traditions, for example in Chinese theory and practice.
Providing a simple and elegant way of generating a musical scale, this tuning system may have a special appeal for styles of harmony where fifths and fourths are the most favored intervals, as is true in the ensemble music of Chinese and related traditions, for example, as well as in medieval European polyphony.
In the West, as the name suggests, Pythagorean tuning was credited to the ancient Greek philosopher Pythagoras, known (like many of the pre-Socratics) mainly through quotations and anecdotes in later writers. Interestingly, it is documented in guides to organ building from the post-Carolingean era (9th-10th centuries), also a period when polyphony was beginning to be recorded.
Remaining the standard theoretical approach in the High Gothic era of the 13th century, Pythagorean tuning seems very congenial to the complex polyphony and subtle harmonic continuum of composers such as Perotin, Adam de la Halle, and Petrus de Cruce. It also nicely fits the style of many 14th-century works, such as the famous Mass of Guillaume de Machaut.
By around 1420 on the Continent, however, musical style had begun to change in ways that invited new tunings. As composers such as Dufay and Binchois emulated John Dunstable, and gave their music an "English countenance" with a more and more pervasive emphasis on thirds and sixths, fashion moved in the direction of intonations that would make these intervals more smoothly blending. By the end of the century, such tunings (e.g. meantone) were becoming the norm in theory as well as practice.
The unsuitability of medieval Pythagorean intonation for Renaissance music should not be seen as a "flaw," any more than Renaissance meantone tuning is "flawed" because it is hardly suitable for the works of Wagner or Max Reger. Rather, techniques of tuning and notation interact creatively with musical style in each period, and should all be taken into consideration in understanding and recreating the music of a given age.
Section 2 presents some basic concepts of Pythagorean tuning as applied to Gothic music, while Section 3 explores how this system nicely fits in with the subtle spectrum of harmonic tension in the 13th century. Section 4 explores some aspects of the tuning in more detail, while Section 5 considers its relationship to other systems of just intonation as well as alternative approaches such as equal temperament.