Minor Keys and Functions
Throughout this book you've dealt with minor keys and chords in a general way. Many of the same basic principles apply to minor keys as they do to major keys. The first step in understanding minor tonality is to look at the key signature. Remember, key signatures tell you how many sharps or flats are in the music. Also, keep in mind that every minor key has a relative major key (that is, a major key that shares the same set of sharps or flats). If you play white notes — together with pitch alterations delineated in the key signature — you will be playing the notes that make up a natural minor and relative major scale (see Chapter 4).
Since this chapter focuses on minor keys, you may disregard the relative major for the moment. The next step in utilizing the natural minor scale is to turn the scale into basic triads, then seventh chords, and so on. Just as in major keys, these chords constitute the chord functions in a given minor key. Figure 18-1 illustrates the outcome of this process.
Figure 18-1.
Chord functions derived from the natural minor scale with sevenths
You'd expect these harmonic derivations from the natural minor scale to be the last word on minor chord functionality; however, they are only the beginning. To be fair, the chords spelled out in Figure 18-1 may be used as the “proper” functions in a minor key. From Renaissance music to Bob Marley reggae classics, these natural minor chord functions have provided the harmonic basis for many songs and compositions. However, more often than not, life in a minor key is more convoluted and complex.
Just what is it about a minor key that makes it different and more complex than a major key?
The most notable difference between major and minor keys and chord functions is how the V chord and vii chord are altered in a minor key. In minor keys, the V chord becomes major (that is, the third of the chord is raised). The vii chord is also rooted on the major seventh scale degree (more akin to the harmonic minor than to the natural minor) rather than the minor seventh degree. When the vii chord is rooted on the major seventh it becomes diminished (now, vii dim or viio). In minor keys, these alterations require the use of accidentals.
By making the V chord major in a minor key and by rooting the viio chord on the major seventh scale degree, the natural minor scale, seen before as our guiding principle, has been diminished in importance. This violation of the natural minor — in favor of alterations to the chords themselves — is accomplished by the use of accidentals. Figure 18-2 shows this adjustment. The harmonic seventh on the i chord is often adjusted in a likewise manner, so here you'll also raise it to the major seventh or leading tone.
Figure 18-2.
Common chord functions in a minor key with sevenths
But what's really going on here? What's happening is that the seventh scale degree is being raised for the V7 and vii dim7 chords. This is exactly like the modification made to the natural minor scale when modifying it to become the harmonic minor scale. This is a great way to conceive of it. The only caveat here is that, in reality, it is probably the scale that comes second, meaning that it is not the scale that dictates to the chord how it should be modified; rather, it is the other way around. In other words, the outcome of the harmonic pressure to modify the V chord from minor to major so that it has the same dominant sound that the V chord has in a major key. Because of this, the natural minor scale gradually morphed to accommodate the raised seventh scale degree. Eventually the harmonic minor scale became an important underpinning in minor keys.
