Learning Objectives
- Examine how triads may be built on any scale degree of the minor scale and can be labeled using Roman numerals.
- Examine the types of triads that occur naturally in minor keys.
Harmony II: Triads in a Minor Key
Triads in a Minor Key
As with major keys, we can built triads on any scale degree of a minor scale. But since two of the scale degrees in minor are variable, the types of triads that can occur in minor keys are more numerous.
Here, triads are built on each scale degree of the D natural minor scale. Click "Show Me" to hear these natural triads.
Triads Built on the Minor Scale
Notice that the tonic, subdominant, and dominant triads are minor (m), the mediant, submediant, and subtonic triads are major (M), and the supertonic triad is diminished (d). None of these qualities coincide with the ones found in major keys.
However, it is much more common to use the leading tone rather than the subtonic when forming triads in minor. The leading tone is introduced to increase the sense of pull towards the tonic. When the leading tone of D minor (C#) is introduced, forming the harmonic minor scale, the quality of the triads in minor changes as follows. Click "Show Me" to hear these altered triads.
Harmonic Minor Scale Triad
Compare the triads in these two examples. What changes were caused by the introduction of the C#? The only chords that were affected are those on scale degrees 3, 5, and 7. Instead of a minor dominant triad (on scale degree 5), there is now a major dominant (a V chord). This is a stronger dominant sound that resolves more convincingly to the tonic triad. The major subtonic chord in natural minor (on scale degree 7) becomes diminished (a viio chord). Note that these two altered triads are now identical to the dominant (V) and leading tone chords (viio) in major keys.
If the leading tone were raised in the mediant triad as well (on scale degree 3), it would create an augmented triad (here spelled F-A-C#). It is quite unusual to find this dissonant-sounding augmented triad in actual music. It is much more likely to appear as a major triad (F-A-C), without the raised leading tone.
There are other possibilities as well. If we were to include the triads created by raising scale degree 6 (the melodic minor scale), all of the following triads would be possible in minor:
Note that there are two possible triads for every scale degree except for the tonic—the most stable harmony and the one to which the other chords gravitate. Although all of these triads are possible, they are not all equally likely. The seven circled triads in the example above represent the triads that occur most frequently in minor keys. These seven most common triads are also provided as a summary in the example below. These are the minor-key triads that you should try to remember.
Note that there are minor triads on scale degrees 1 and 4, diminished triads on scale degrees 2 and 7, and major triads on scale degrees 3, 5, and 6. This chord pattern is the same for all minor keys (as outlined in the rule below). Notice that the all of the roots of these triads belong to the harmonic minor scale. In fact, all of the pitches in these triads belong to the harmonic minor scale with the single exception of the 5th of the mediant triad (marked *).
| Remember |
|
Roman Numerals in Minor
Like major-key triads, the triads in a minor key can also be labeled using Roman numerals, as illustrated in the example below. This pattern of Roman numerals is the same for all minor keys.
Take a moment now to compare the Roman numerals for the diatonic chords in minor keys (as shown above) with those for major keys (given below). The V and viio chords are the same for both major and minor, but all of the others are different. Memorizing these two sets of Roman numerals will be very useful in doing harmonic analysis, which is the topic of the next lesson.
