Inquiry-Based Music Theory OER Text Book

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17a Examples - An introduction to mode mixture

Tonal harmony is easiest to study when when it follows strict rules, and because of this, we have studied harmonic function thus far through the lens of major and minor keys. In real music however, the relationship between modes is more fluid. Look at the following chart of the chords of parallel major and minor keys. How many common chords are there? Are these closely- or distantly-related keys?

C major Chord Chord C minor
I C maj C min i
ii D min D dim iio
iii E min E-flat maj III
IV F maj F min iv
V G maj G maj V
vi A min A-flat maj VI
viio Bo Bo viio

You will notice that the only common chords are the dominant function chords, and even these require alteration to share function. So if we think about this as we did when discussing modulations, these keys should have little in common. On the other hand look at the following basic progressions in both keys. Do these look unrelated? How does the voice-leading differ between the two? How many chromatic pitches are required to make the second progression function?

Borrowing from the parallel minor

When studying the voice-leading of these two parallel modes, they seem almost interchangeable.

So try it.

Alter the following progression in C major to “borrow” the VI and iio chords from minor. What chordal members do you have to alter for each chord? What scale degrees are these? When you play it back does it sound acceptable? What if you only alter the vi chord? Or the ii chord?

The next progression is a longer example containing multiple cadences. What could you alter here to borrow chords from the parallel minor?

Borrowing from the parallel major

The next example uses the same progression in minor. Alter one chord at a time to borrow it from the parallel major, and pay careful attention to which scale degrees you are altering. Which progressions sound acceptable to you? How does the voice-leading change when starting in minor? Pay careful attention to any enharmonically equivalent resolutions.

Roman numeral notation of mode mixture

It is because of mode mixture that we have followed such strict guidelines when labeling Roman numerals to this point. By having each part of a Roman numeral describe an isolated chord tone, we are able to accurately describe even borrowed chords.

Chordal member Default implied pitch To raise by semitone from default To lower by semitone from default
root diatonic scale degree sharp symbol in front of Roman numeral* flat symbol in front of Roman numeral*
third based on case of Roman numeral upper case (M3) lower case (m3)
fifth P5 above root add + after Rom num add o after Rom num
seventh m7 above root add M before inversion figure add o before inversion figure**

*For clarity’s sake, we always use a sharp or flat symbol to show that we are raising or lowering the root, even if you are actually adding a natural.

**Because the diminished o implies the interval of a d5 AND a d7, you must use the half-diminished symbol if you wish to alter the fifth but leave the chordal seventh as a m7 above the root.

Test your knowledge of this by writing the correct borrowed chords for every diatonic chord in a parallel major and minor. You may use the following chart as a model. With all of these make sure that you build the chord off of the correct root. For example, students often forget that to build a major VI chord in major, the root is altered thereby changing the entire chord. (In C major for example, the borrowed bVI chord is not an A major triad.)

Roman numeral in major Borrowed from parallel minor Roman numeral in minor Borrowed from parallel major
I   i  
ii   iio  
iii   III  
IV   iv  
V   V  
vi   VI  
viio   viio  

Commonly used mode mixture

As you discovered above, certain chords do not sound good – or function at all – when borrowed. Because of this, there are a few chords that are borrowed most often.

Because of voice-leading resolutions, it is easiest to borrow chords while in major. The most commonly borrowed chords in major are:

  • viio7 (requires lowered ^6)
  • iv (requires lowered ^6)
  • iiø7 (requires lowered ^6)
  • iio (requires lowered ^6)
  • bVI (requires lowered ^6 and ^3)
  • bVII (requires lowered ^7)
    • Be careful to look at the function of this chord. Label it as V/III if it resolves to a borrowed bIII chord. Label it as bVII if it resolves in any other way.
  • bIII (requires lowered ^7 and ^3)

Minor is more limited due to voice-leading limitations, but the following chords are commonly borrowed:

  • I (requires raised ^3)
    • This is often used to end a minor piece in Baroque and Classical music. It is used often enough that it has a unique name: the Picardy (Picardie) third
  • IV (requires raised ^6)
    • Commonly results when used in first inversion to create a scalar bass line of sol-la-ti-do
  • #vi (requires raised ^6 and ^3)
    • Commonly results when used in root position to create a scalar bass line of sol-la-ti-do