Grade Six Music Theory Composition: Lesson 6 - Modulation

What is Modulation?

“Modulation” is an important sounding word which just means “change of key”. A modulation can happen with or without a change in key signature. In fact, most modulations don’t require a change of key signature.

Generally the key signature is only changed when a significantly long portion of the piece is in a different key. Most often, the key changes only last for a certain number of bars, and then the melody returns to the tonic key (or modulates again).

You can sometimes tell that a piece has modulated when there are lots of accidentals on the page!

In the Grade Six music theory exam, modulation can happen in your composition in one of two ways:

• The melody will modulate towards the end and will finish in the new key. (In this case, your melody is in fact just a section of a larger, as yet unwritten, piece.)
• The modulation will happen at the end of the antecedent phrase, and will return to the original key by the end of the piece. (In this case, the piece itself is complete.)

In recent Grade Six music theory exam papers, there has been a choice of questions which is either to

• write a piece which must modulate and finish in the new key (i.e. is unfinished)
• write a piece which is complete (i.e. ends in the original key) with modulation optional.

Be careful when choosing the question, because the key your piece ends in will depend on which option you choose.

The Mechanics of Modulation

Modulation is usually achieved through the combination of two techniques:

1. a pivot chord, followed by 
2. a V-I progression in the new key

1. A pivot chord is one which exists in both the old and the new key. For example, the chord of C major exists in the key of C major as chord I, G major as chord IV, F major as chord V and E minor as chord VI.

Let’s say that our piece modulates from C major to G major (the dominant key).

The chords I, iii, V and vi in C major also exist in G major as IV, vi, I and ii. 

You need to pick a pivot chord, then use it as a stepping stone to reach the new key.

2. The next step is to confirm the new key.

This is most effectively done by writing a V-I progression, with the leading note moving to the new tonic. For example, we write an F#-G in the melody. Remember we are now in G major, so the V-I progression is D major to G major. F# is outside of the C major scale, so it helps us to understand that we are in a new key. 

It’s always helpful to try to include any notes from the new key which didn’t exist in the original one. If we modulate from C major to F major (to the sub-dominant), the leading note to tonic progression is not as striking as it was in the previous example, because the notes E-F exist in both C major and F major. However, we could include a Bb in our melody (for example, Bb-A-G-F as a falling scale), for a similar effect.

The dominant 7th chord is also very useful when you modulate, as often it contains a note which is alien to the old key. If you modulate from C major to F major, and you use V7-I, the V7 chord contains Bb, which could not occur in C major.

Choose your melody notes carefully - make sure there is no ambiguity of key by including notes which are unique to the new key and not present in the old one.

Where to Modulate to?

In the Grade Six music theory exam, the key you have to modulate to will be one of these four:

• to the dominant
• to the sub-dominant
• to the relative major
• to the relative minor

Of course, in real life it’s possible to make your music modulate to any new key under the sun. You can make C major modulate to F# major, if you really want to! We will stick to these four for now though.

In all of these modulations, there will be four possible pivot chords, and only one note which needs to be chromatically altered in the new key (unless it's minor - see below!)

Here is a list of the pivot chords for each modulation: 

Examples:

• If you want to modulate from D major to the dominant key, A major, you could use chord V in D (A major) which would become chord I in A major. Include a raised 4^th (=G#).
• If you want to modulate from C# minor to the relative major, E major, you could use chord iv in C# minor (F# minor) which would become chord ii in E major. Lower the 7^th (=B natural from B#). 
• If you modulate from C major to A minor, the relative minor, you could use chord vi in C major (A minor), which would become chord i in A minor. You should raise the 5^th (G#), and might also have to raise the 4^th (F#), if you’re using an ascending melodic minor scale. 

It’s worth noting that some of these pivot chords are based on primary chords (I, IV or V). You will find them easier to use in most cases, because the primary chords are more effective at fixing the new key in our minds. (For the same reason that they are used at the beginning of a piece.)

You don’t need to learn that table off by heart, by the way! The quick way to work out your pivot chords is to simply write out the letter names of the scale in the original key (e.g. A major): 

Then write the letter names of the new key directly underneath (we’ll put the sub-dominant, D major): 

Cross out the column which contains notes with a different accidental (G-G# here). The notes you have left can be used in triads in both keys.

There will be four triads – write them out so you don’t forget them!

Examples

This is a complete piece – Gavotte from Suite No.6 by Richard Jones.

The key is G major.

• In bar 4, chord I of G major becomes the pivot chord IV of D major. (The first E is an accented passing note).
• Chord V of D major is immediately introduced, consolidating the new key.
• The C#, which is not a note in G major so is unique to D major, helps to fix the new key.
• The phrase ends with a perfect cadence in D major.
• The next section begins in D major, but the third beat of bar 5 is a pivot chord; I in D major or V in G major.
• The C natural helps to confirm that we are returning to the key of G major.
• It’s also interesting to note the interpolation section in bars 7-8.
• The piece ends with a perfect cadence in G major.  

 Our second example is from the Haydn Andante we looked at earlier, when discussing cadences. We’ll revisit it, to study how the modulations were achieved. 

• The piece starts in Bb major, and the first phrase ends with an imperfect cadence in Bb major in bar 4.
• Bar 5 contains the pivot chord I in Bb major, which is IV in F major.
• Bar 6 is chord V in F major – the dominant key.
• The E naturals in bar 6 help to fix the key, and also create a V-I progression from bars 6-7.
• The section ends in the new key, with a perfect cadence. This is not the end of the piece. In the next section, the key will modulate back to Bb major.

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