Minor scales: a hug and a kiss, or just a handshake?
During my first ten years of piano study, starting at age five, the term diatonic scale was never taught to me.
Nor had I realized that there existed an entity called a natural minor scale, inasmuch as I had been directed to practice only major, melodic minor, and harmonic minor scales as part of my daily practice regimen at the keyboard.
Additionally, the reason for the existence of two altered minor scale versions—melodic minor and harmonic minor—had not been explained to me: namely that composers wanted to correct for what they perceived as a weakness in the natural minor scale; specifically, that the 7th and 8th degrees of that scale were a whole step instead of a half step apart. Consequently, there was an absence of the leading tone and any leading-tone effect in music based upon the natural minor scale.
I have long had a sense that many piano teachers have not given much thought to the above, because they, like my own excellent first piano teacher, have viewed scales mostly—if not entirely—as practice material for building technique. Students who only learn skills through technical practice may likely miss the knowledge that composers have always based their music on scales. An understanding of this perspective would greatly enhance students' musicianship.
What I teach
When I teach, I want my students to under-stand the following:
Major and minor scales, which formed the basis of most tonal music composed from the seventeenth through the nineteenth centuries, evolved from two of the seven medieval modes: the major scale from the Ionian mode (represented by the white keys from C to C on a piano), and the natural minor scale from the Aeolian mode (the white keys from A to A on a piano).
Major and natural minor scales are both diatonic scales; they each contain seven different tones, with the tonic repeated at the octave, moving from one alphabet letter to the next, without omitting or repeating a letter. They are written on a musical staff by moving from line to space in succession, without omitting or repeating a line or space. Each scale contains five whole steps and two half steps, though the order of the steps varies.
In the major scale, the close proximity of scale degrees 7 and 8 (a half-step apart) creates the sense, both in the scale and in music based on the scale, that 7 wants to lead to 8 with a strong sense of urgency. In fact, when scale degree 7 is only a half step away from scale degree 8, scale degree 7 is referred to as the leading tone. By contrast, when 7 is a whole step away from 8, it is referred to as the subtonic.
In the natural minor scale, because there is a whole step between scale degrees 7 and 8, there is a far less compelling sense of 7 wanting to move to 8. I still get a kick out of the humorous distinction that Leonard Bernstein once made regarding the difference between the last inter-val of the major and natural minor scales. In one of his Young People's Concerts, Bernstein said that in the major scale, 7 wants to hug and kiss 8. In the natural minor scale, 7 wants only to shake 8's hand.
I remind my students that the word natural in the term natural minor scale has nothing to do with sharps, flaps, or naturals. The word natural in this context means pure, as in the pure minor scale, before any alterations. I tell my students that even though composers loved the minor scale, they felt that it possessed a serious flaw. The perceived weakness was that scale degree 7, without a leading-tone effect, was not effective melodically or harmonically. Composers "corrected" for that weakness by inventing two altered minor scales: the harmonic minor scale and the melodic minor scale.
The harmonic minor scale raises the 7th note of the natural minor scale one half step, and it employs the same pitches descending as ascending. The key sig-nature of the harmonic minor scale is the same as that of the natural minor scale. An accidental (either a sharp or a natural) raises the 7th scale degree within the body of the music, without affecting the key signature, as seen in the example below. I have my students note the interval of an augmented 2nd between scale degrees 6 and 7 in the harmonic minor scale. This is a characteristic sound of this scale, frequently found in music from the Middle East.
I play the following musical example for my students, so they will better appreciate the distinctive sound of this interval and its relation-ship to music from that part of the world.
The melodic minor scale is unusual, given that it employs different pitches descending from those ascending. Ascending, the 6th and 7th notes of the natural minor scale are each raised one half step. Descending, however, those raised pitches are each lowered one half step, thus restoring them to the pitches of the original natural minor scale. The melodic minor scale also employs the same key signature as the natural minor scale, and the altered pitches are written using accidentals within the body of the music, as seen in the example below.
I use the following musical example to demonstrate this scale, asking students to notice the raised 6th and 7th degrees (C# and D#) that revert back to the lowered 6th and 7th (C natural and D natural) when descending.
I also talk about the fact that most minor key music performed in concert halls utilizes the pitches of harmonic minor and melodic minor rather than natural minor. If a composer were to employ the pitches of the natural minor scale, as seen in the cadence below, the resulting music would likely sound either like folk music or music from much earlier centuries. This is especially apparent when it comes to cadences—resting points in a musical phrase, section, or composition.
By contrast, here is a cadence using the notes of the harmonic mi-nor scale. This has a much more familiar, more recent sound, historically speaking.
Dominant 7th chords
In a major scale, the dominant 7th chord occurs naturally when you build a seventh chord on the 5th (or dominant) scale degree. This chord, called a dominant seventh chord, naturally contains a major triad with a minor 7th above the root. This chord, which contains the interval of a tritone, wants to resolve to the tonic chord. In a G7 chord, for example, the tritone pitches are B and F and naturally want to resolve to C and E.
In a natural minor scale, however, the seventh chord built on the dominant scale degree naturally contains a minor triad with a minor 7th above the root. This chord does not have the sense of urgency or the need to resolve, as it doesn't contain a tritone or any leading-tone effect. In order to provide this effect, the natural minor scale has to be changed to a harmonic minor scale, with a raised seventh. This creates a dominant-quality seventh chord with a strong desire to resolve. I believe it is important for students to understand the role the harmonic minor scale plays in creating tension and resolution, particularly at cadences.
In conclusion, I believe that scales should be used in a broader teaching context, and not just for technical practice. Their theoretical aspects are not only interesting from an intellectual standpoint, but they are also valuable in developing students' overall musicianship.