Introduction

Unlike the major scale, the minor scale has different forms:

• natural minor
• harmonic minor
• melodic minor

Each form of the minor will be used interchangeably through a piece of music in a minor key. We will outline the structure of each of these before going into more details.

Minor Scale Forms

Minor scale forms all retain a basic structure in their lower tetrachord.  This involves the tone-semitone progression T–S–T, which contrasts with the major scale’s T–T–S. The variability in minor scales forms is exclusively found in the upper tetrachord—that is, scale degrees to .

The Natural Minor

The natural minor scale is identical to the Aeolian mode.  It can be produced on the white-key notes of the keyboard with a starting pitch on A (Example 1).

There are some distinctive differences to the major scale:

• The numbering and naming of degrees is mostly the same, but the sol-fa syllables have shifted—in minor scales we usually locate the tonic on the syllable la. This shift in sol-fa syllables is true across all the minor scale forms.^[1]
• The seventh degree () is a tone below the upper tonic, rather than a semitone and it has a different name—it is called the subtonic. Unlike the leading note in the major scale, the subtonic’s tendency to move toward the tonic is not as strong.

The Harmonic Minor

The harmonic minor differs from the natural minor in that the seventh degree is raised by a semitone from its natural diatonic position.  As such, the seventh degree now lies a semitone below the tonic and is referred to as the leading note (same as for the major scale).  Like in the major scale, the leading note provides a strong tendency to move toward the tonic.

The following points should be noted about the alteration of the seventh degree to become the leading note:

• We now write its scale-degree number as ♯.^[2]
• This alteration is never included in the key signature of minor scales, it is always made by adding an accidental.
• Raising the subtonic to become the leading note changes the tone-semitone series in the upper tetrachord, creating a larger interval between the sixth (submediant) and seventh (leading note) degrees, equal to a tone plus a semitone—this is T+S and shown in green in Example 2.
• The sol-fa syllable for the leading note in the harmonic minor is si (pron. “see”).

The Melodic Minor

The melodic minor has two sub forms: ascending melodic minor and descending melodic minor.  As the distinction implies, the ascending form goes up and the descending form goes down.^[3]

The following should be noted about the melodic minor:

• The descending form is the same as the natural minor
• The ascending form “smooths out” the upper part of the scale while retaining the leading note by also raising the sixth degree, which is now called the raised submediant (♯). This reduces back to a tone the T+S interval between the sixth and seventh degrees that is found in the harmonic minor, while increasing the interval between the fifth and sixth degrees from a semitone to a tone.
• The sol-fa syllable for the raised submediant in the melodic minor is fi (pron. “fee”)

A composite minor?

As noted at the start of this chapter, the variations to the organisation of the minor scale are restricted to its upper tetrachord.  What is important about this is that it is not just the two changeable degrees (the sixth and seventh degrees) that that we need to attend to, but we also need to understand the intervallic relationships that change when these notes do, particularly in relation to the dominant and tonic degrees that bound them on either side.

As you get further through your understanding of minor scales, the reasons for this variability will become clearer, as will understanding why composers use one form or the other and what you should choose when you write music.

It is useful, for the movement to understand that it is the lower tetrachord which gives the minor scale it distinctive modal flavour while the upper tetrachord presents a kind of menu of notes and degree relationships (S, T, T+S) whose use will be determined by various rules, tendencies and taste. We can think, therefore, of a kind of overall composite minor scale, with a diatonic lower tetrachord and a chromatic upper tetrachord.

Major-Minor Relationships

There are two ways in which major and minor keys are related—relative and parallel:

• Relative major and minor keys share the same key signature.
• The tonics of relative keys are a minor third (a tone plus a semitone) apart.
• Parallel major and minor keys share the same tonic.
• The key signatures of minor keys are different

Both relationships are important, but have significant differences.  Broadly speaking, the relative major-minor relationship is expressed in the diatonic realm (allowing for altered sixth and seventh degrees) while the parallel major-minor relationship is expressed in the inherently more complex chromatic realm of “modal mixture”—a topic for much later in this book.

Relative major-minor relationship

Relative major and minor scales have their tonics a minor third apart. Specifically, the tonic of a minor scale is a minor third lower than its relative major.  This relationship is reciprocal.

A simple way to work out relative major and minor scales is to remember that the sol-fal syllables for their tonic degrees will be do and la on the same overall scale—i.e., the relative minor key’s tonic will be la to the relative major key’s do.

This is shown below for F major and D (natural) minor. Both keys have a signature of one flat (B♭), D is a minor third below F.

There is a high degree of consistency in the sol-fa syllables in the relative major-minor relationship.  To produce the various forms of the minor scale, all we need to do is alter fa to fi and so to si, as necessary.

Parallel major-minor relationship

Although parallel major and minor scales share the same tonic, their relationship is aurally more complex as there is greater variety in their pitch content, and their sol-fa syllables are quite different.  This is shown below in relation to F major and F (natural) minor.

Note that, from the major to the natural minor, the third degree mi become ma, the sixth degree la becomes lor, and the seventh degree ti becomes ta. For the ascending form of the melodic minor, the raised sixth and seventh degrees revert to the major-scale syllables la and ti, respectively.

All the sol-fa syllables for the various scale degrees between the major and the relative and parallel minor scales are given in the table below:

degree number	degree name	major	relative minor	parallel minor
	tonic	do	la	do
♯	leading note	ti*	si	ti
	subtonic		so	ta
♯	raised submediant	la*	fi	la
	submediant		fa	lor
	dominant	so	mi	so
	subdominant	fa	re	fa
	mediant	mi	do	mi
	supertonic	re	ti	re
	tonic	do	la	do
		*la and ti  occur diatonically on the sixth and seventh degrees in major

Minor key signatures

We can use the circle of fifths to set out the key signatures as they are shared by relative major and minor keys.  To do this, we show minor keys inside the circle, aligned with their relative majors on the outside.  These are shown in red in Example 7, and also in lowercase (following a convention of labelling major keys with uppercase letters and minor keys with lower case).  Or, the minor tonic’s note is la to the major tonic’s do.

Looking at the circle of fifths and finding the same tonics inside (minor) and outside (major) also shows the distance of the parallel major-minor relationship.  For any major tonic, its parallel minor tonic will lie a full quarter turn anti-clockwise around the circle.  For instance, C major (key signature of no sharps or flats) is at “twelve o’clock” while C minor (key signature of three flats) is at “nine o’clock.”

Correspondingly, for any minor tonic, its parallel major tonic will lie a quarter turn clockwise around the circle. For instance, B minor (key signature of two sharps) is at “two o’clock” which B major (key signature of five sharps) is at “five o’clock.”