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Part-writing In Minor Keys I

Part-writing in minor keys follows the same basic principles and patterns already discussed in previous Hubs in this series, for the most part (no pun intended!) However, there are more possibilities and complications involved—otherwise, we wouldn’t have deferred dealing with the minor up until now!

Before we tackle minor key part-writing, though, take a moment to consider whether you are ready. This Hub assumes quite a bit of knowledge on chords, their voicings, and on part-writing. Below are summaries of the preceding Hubs; if you feel unfamiliar with any of the material you may be wise to go back and work through the relevant parts.

Part-writing Hub #1

  • Lead sheet
  • “Spacing” of voices
  • Parallel and contrary motion of voices
  • Concept of “voice leading”
  • “Root position,” “voicing,” and “line”
  • Polarized roles of tonic and dominant chords in Classical harmony
  • Resolution of “leading tone”
  • “Open” versus “close” chord spacing
  • Chordal “doubling”
  • “Common tone”

Part-writing Hub #2

  • Vocal ranges
  • Rule for determining sharp keys from key signature
  • Rule for determining flat keys from key signature
  • Chords with missing thirds
  • Part-writing Chords: Subdominant I
    Third in a series, this Hub examines the use of the subdominant chord--the "IV chord"--in traditional ("common-practice") harmony, with practice exercises.

Part-writing Hub #3

  • Root motion by fifth
  • Root motion by second
  • Parallel motion [perfect or imperfect intervals]
  • Similar motion; similar fifths and octaves
  • Incomplete triads [omitted fifths]
  • Tripled root voicing

Part-writing Hub #4

  • Primary and secondary triads
  • “Doc Snow rule of doubling”—better known in association with Walter Piston!
  • “Hybrid spacing”
  • IV normally precedes ii in Classical style
  • Chord substitution
  • Deceptive cadence
  • Voice overlap
  • Part-writing Chords: Mediant and Submediant I
    The triads built upon scale degrees 3 and 6--the mediant and submediant chords--are the least common but also the most colorful diatonic triads. Learn (and practice) their common patterns of usage here!

Part-writing Hub #5

  • Using mediant and submediant chords (iii & vi)
  • "Falling fifths" progression
  • Chord substitutions
  • Melodic fault #1--Leap Greater Than A Octave
  • Melodic fault #2--Leap Outlining Dissonant Interval
  • Melodic fault #3--Three Consecutive Leaps Or Skips In The Same Direction

Let’s start our exploration of minor key harmonization by looking at minor scales. There are three basic forms, which we will consider in turn. The first is given below together with its “parallel” major scale—that is, the major scale built upon the same tonic. C Major is on left; C (natural) minor on the right—the accidentals are given for emphasis.


As shown, the simplest form of the minor scale is the “natural minor.” This form simply consists of the key signature’s unaltered diatonic notes, and it is equivalent in content to the modal scale called “C Aeolian.” Differentiating between “C natural minor” and “C Aeolian” here would be tedious at best and confusing at worst, so, having noted that an alternative term exists, we will pass quickly on, leaving grumbling theory purists behind us!

We’ve noted previously that common-practice harmony is “polarized” between a stable tonic triad—the goal of all harmonic motion—and an unstable dominant, which ‘wants’ to resolve to the tonic. Thus the single most important harmonic progression in that style is I-V-I, which was accordingly the subject of the very first part-writing Hub. But the characteristic ‘drive’ of that progression depends very much upon the leading tone—that is, the seventh scale degree of the major scale. In the natural minor scale we don’t have a leading tone—the seventh of the natural minor scale is a tone, not a semi-tone, below tonic and doesn’t ‘pull’ toward tonic in the same way. Compare tonic-dominant-tonic with major and minor dominant chords:


Throughout the common-practice period—actually, from long before it—composers tended to raise the seventh scale degree by either a sharp or a natural sign, recreating the wished-for leading tone. This restores the ‘drive’ toward tonic. When this alteration of the seventh scale degree is carried out consistently, the result is another form of the minor scale, called the “harmonic minor”:

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You may find in the sound of the harmonic minor scale a distinctly different ‘color’—exotic, perhaps, or simply more ‘emotional.’ This results from the interval between the sixth and seventh scale degrees. Technically, it is called an “augmented second,” and it has been regarded as difficult to sing, difficult to ‘understand’ aurally, dissonant, and (traditionally) better avoided. Opinions may differ on some of these assessments today, but the historical fact is that these judgments led to the rule that the augmented second should be avoided in most circumstances.

This meant in turn that the harmonic minor scale, though a useful guide to building minor-key chord, wasn’t useful melodically. For that purpose, yet another form of the minor scale became conventional:


This version of the minor scale, exceptionally, differs in its ascending and descending forms. The former is driven by the leading tone’s inclusion—to avoid the augmented second with the leading tone, the sixth degree of the scale is raised as well. This leaves only the third degree, the mediant, differing from the parallel major. By contrast, in descent the scale does not use the leading tone, since it is not going to be resolving to tonic in any case. Without the leading tone, there is no necessity to change the sixth scale degree, and therefore the descending harmonic minor does not differ from the natural minor scale.

(By the way, in practice, minor-mode pieces usually mix the various forms of the scale—pieces are not normally written in (for example) “D harmonic minor” or “F# melodic minor.” It should just be “D Minor” and “F# minor,” respectively.)

So the three forms of the minor scale have different functions, as summarized in this table:


Of course, these functions do not cover every instance—in particular, though most chords in minor conform to the harmonic minor scale, not all diatonic minor chords do. That raises the question, how many of the diatonic chords can be affected by alterations either to scale degree six or scale degree seven? Or, to put it in the obverse case, how many chords are unaffected?

The answer surprised me, when I first thought about this. Take a moment yourself—what is your answer to these questions? If for you (as for me) manuscript paper is a handy tool in thinking such things through, you can print some via the sidebar link.

The three forms of the minor scale are given again for convenience.


Working systematically through the scales (really, the melodic form is the only one we need to look at), we find the following:


So the only unaffected triad is the tonic! That means a potential diatonic ‘inventory’ of thirteen chord forms, as opposed to only seven for major keys—perhaps you can now see why minor was left until now.

Luckily, there is a convenient approach to this new complexity. We’ll simply recap previous Hubs, pointing out issues, differences and possibilities as we go. As in previous Hubs in this series, we’ll focus more on using common part-writing patterns, and less on avoiding infractions of part-writing rules—even though we will mention those rules as we go.

And as in previous Hubs, I urge you to work through examples on paper—if you avoid the temptation to ‘look ahead’ to the answers given, you’ll learn a lot more and remember a lot more. Discipline, as usual, will be rewarded by achievement—dreary, but there it is. (The sidebar link above is a quick source of manuscript paper, if you need some.)


The main challenge here is remembering to raise the leading tone. It is easy to forget, and makes a big difference to the sound, as we saw above. Let’s practice a few of the patterns we looked at in Part-writing Chords: Tonic and Dominant I.

The first pattern we learned, way back in that Hub, was a three-chord pattern—tonic-dominant-tonic—in which the soprano followed a “1-2-3” line, as shown below.

See if you can still part-write this progression as if in major. (Use open-spaced chords for this question.) When done, locate the leading tone—it will be somewhere in your dominant chord, of course—and make sure you have raised it with a natural sign. That will be the last thing you need to do in this question, since, for tonic-dominant progressions, raising the leading tone is the only ‘new’ challenge.

As usual in this series of Hubs, the answers are given below, with one voice added at a time in the sequence bass-alto-tenor, and followed by a video example you can listen to, as above.

Let’s try a more challenging instance. What is the (minor) key and scale-degree pattern of the soprano below?

Question 2.

Question 2.

The correct answer is that this is a D minor 3-2-1 soprano line. Continue by supplying the other three parts in the usual order.

Here’s another version. What is the key and scale degree pattern?

Question 3.

Question 3.

It’s 5-5-5 in B minor. Add the other parts, as before.

One more variation on tonic-dominant-tonic. What is the key and soprano line?

Question 4.

Question 4.

F minor, with a 5-7-1 line. Here, the raised leading tone is already given, so you don’t need to worry about anything except the part-writing patterns.

As implied above, though, there are times when the minor form of the dominant may be written. Most theorists would say that the minor form does not function as a true dominant. In fact, that is one potential advantage of using the minor form: if we think of harmonic tension as kind of energy, then the normal ‘shape’ of common-practice musical phrase is a gradual build-up of energy, culminating in its release with a “cadence”—a stereotypical harmonic/melodic/rhythmic pattern signaling to listeners the phrase’s end. But the dominant is the normal high point of harmonic tension; once we write the dominant chord we don’t have many options for building more energy from there!

This is often addressed in the harmonization of a line descending from tonic: in major, the unresolved leading tone is harmonized with iii instead of V. The corresponding manoeuvre works in minor, too:

Example 10.

Example 10.

Notice how during the tricky “III-iv-V” passage the upper voices move in contrary motion to the bass. As we saw previously, this is the first thing to try when you have root motion by second.

But there’s another option, as well—in minor we can avoid getting to a dominant ‘too soon’ by writing the minor form of the dominant, v, instead of III: