Thirteenth-Century Polyphony

2. Two-voice intervals and progressions

Rather as 3-D graphics can be seen as a logical extension of 2-D drawing techniques, so music in any period for three or more voices reflects certain artistic assumptions about the nature of elementary two-voice intervals. The 13th century is no exception.

2.1. A subtle continuum of tension

Two-voice intervals range along a subtle scale of tension from the most purely blending to the most strongly discordant. While such distinctions are often relative, the absolute distinction between stable and unstable intervals is vital:


Purely blending         (1, 8)
Optimally blending      (5, 4)


Relatively blending     (M3, m3)
Relatively tense        (M2, m7, M6)
Strongly discordant     (m2, M7, tritone - and often m6)

Stable intervals, and especially the fifth, represent points of ideal concord and rest, often serving as goals of directed cadences. The more tense an unstable interval, the more urgently it suggests resolution to a stable concord - an expectation often but not always immediately fulfilled.

In two-voice music, the fifth is both optimally euphonious and conclusive, while the fourth is relatively stable but somewhat less conclusive. However, two-part pieces often begin or end with a purely blending (although less sonorous) unison or octave.

2.2. Directed cadences

The most powerful two-voice progressions in this period involve moving from an unstable interval to a stable one by stepwise or near-stepwise contrary motion. Either both voices move by step, or one moves by step and the other by a third. Here are examples illustrating some of the most important resolutions:

m2-4   m2-5      M2-4   M2-5     m3-1   m3-5     M3-1   M3-5
---   ----      ----   ----     ----   ----     ----   ----
c'-d'  f-g       b-c'   g-a      g-f    g-a      a-g    a-b
b -a   e-c       a-g    f-d      e-f    e-d      f-g    f-e

m6-8   m6-4      M6-8   M6-4     m7-5   M7-5
---   ----      ----   ----     ----   ----
c'-d'  f'-e'     e'-f'  a'-g'    d'-c'  e'-d'
e -d   a -b      g -f   c'-d'    e -f   f -g

(Notation graphics: m2-4, m2-5, M2-4, M2-5, m3-1, m3-5, M3-1, M3-5, m6-8, m6-4, M6-8, M6-4, m7-5, M7-5)

In two-voice music, these progressions give a sense of directed and unifying motion. In music for three and four voices, they serve as the elementary building blocks of many powerful and beautiful cadences, as we shall see.

2.3. Obliquely resolving sonorities

Additionally, unstable intervals have standard resolutions where one voice remains stationary while the other moves by step or by a third (sometimes with the middle tone filled in). Here are some of the most common cases:

m2-1   M2-1      m3-1       m3-5         M3-1      M3-5
---   ----     -------   ---------     -------   --------
f-e    a-g      f-(e)-d   c'-(d')-e'    a-(g)-f   b-(c')-d'
e -    g -      d     -   a       -     f     -   g      -

m6-5   M6-5     m7-8        m7-5        M7-8      M7-5
---   ----     ----      ---------     ----    --------
f'-e'  d'-c'    c'-d'     f'-(e')-d'    e'-f'   e'-(d')-c'
a  -   f  -     d  -      g       -     f  -    f       -

(Notation graphics: m2-1, M2-1, m3-1, m3-5, M3-1, M3-5, m6-5, M6-5, m7-8, m7-5, M7-8, M7-5)

2.4. Summary

The music of the 13th century boldly exploits the entire spectrum of intervals from the most blending to the most aggressively discordant. While the distinction between stable and unstable intervals is absolute, there are various degrees of tension among the unstable intervals. Thus M3 and m3 are relatively blending but have some tension, while M2 and m7 are rather tense but have some "compatibility."

Given this approach of flexibility and bold contrast, we should not be surprised to find an amazing variety and richness of multi-voice combinations and cadences.

To Section 3 - Multi-voice combinations.

To Table of Contents.

Margo Schulter