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.

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 use of a “pivot” chord. A pivot chord is one which exists in both keys.
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.

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

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.

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 sharpened 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. Flatten the 7^th (=B natural). 
• 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 sharpen the 5^th (G#), and might also have to sharpen 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!

If you decide to modulate at the end of the antecedent phrase, you must remember to return to the original key by the end of the piece. If you modulate to the dominant, (e.g. C major to G major), you will need to modulate again from G major back to C major. (You should notice that this is now a modulation to the sub-dominant.) Similarly, if you modulate to the sub-dominant in the antecedent phrase, you’ll need to modulate to the dominant in the consequent phrase.

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 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, 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.