Prior Knowledge: Scales, keys, perfect & imperfect cadences.

Content of Lesson: Identifying keys via examining accidentals and cadences, and identifying appropriate modulations from a given melody.

A Quick Note on Harmony Exam Tasks

Throughout this lesson I will make reference to the UK’s A-Level exam tasks and the differences between boards. If you are studying for another reason, these differences are not important however if you are studying for a specific board make sure you know what your task will look like!

Before you Begin

If you are given a melody to harmonise, your first instinct might be to start devising and writing your harmonies immediately. This is unwise as you will run into errors where you have not considered possible key changes. The best way forward is by planning in advance – you should know where the modulations will occur, which keys you need to move through and how you will return to the tonic (unless of course you find your tonic key is minor, in which case ending in the relative major is quite plausible).

To begin your planning:

1. Make sure that before you identify the key at the start of the excerpt. If you are preparing for an exam, you may be given a harmonised opening – check the chords as well as the melody to make sure you know what key you are in. If your exam board gives you only one part, you must make a judgement using that part.
2. Create a key relationship diagram from your tonic key (See Lesson 1: Chords and Keys). This will help guide you on which keys you can modulate to.

Once you have this information, you are ready to plan out your modulations.

Identifying A Change in Key

There are three key features that can help you identify if the key has changed:

• Accidentals
• Presence of tonic/dominant notes
• Cadence patterns (fingerprints)

Using these three indicators will give you a very solid idea of where the melody has moved from and to. If you are not yet familiar with cadence fingerprints, please first look at Lesson 5: Perfect Cadence Fingerprints and Lesson 6: Imperfect Cadence Fingerprints.

There is also an important rule we will follow for chorale harmony: you can only modulate to a closely related key. You may recall this diagram from Lesson 1:

Our rule on modulating only to closely related keys means that if you are in C major, you may only move to one of the keys in the above diagram, usually one step at a time (in this case, modulating from C to either F, G Am). What happens if you want to modulate from C to Em, I hear you ask? In this case, there are two options:

1. You could use a passing modulation first to either G or Am, and then complete a second modulate to Em. A passing modulation is a modulation that has not been confirmed by a cadence, and so you never arrive home in your new key but pass through it to another, more distant key. This is the smoothest way to modulate to a key that is more than one step away.
2. You can use pivot chords to quite literally pivot into the new key. Pivot chords are chords that exist in both the current key and target key, in this example in both C major and Em.

Before we move on, we must ensure we understand both methods. They both require the use of at least one pivot chord, but are both different in approach. 

Passing Modulations and Pivot Chords

Passing modulations are those that are not confirmed by a perfect cadence. In standard modulations, we would subtly (usually!) move into the new key and the presence of a perfect cadence would confirm that we have modulated. 

In passing modulations, there is no confirmation because they are usually only temporary – on the way to another key or on the way back to the previous key, the composer having chosen to add flavour to his harmony for a brief moment with the use of another key.

Modulating Smoothly with Pivot Chords

The use of at least one pivot chord is key in ensuring smooth modulations. As these exist in both keys, you produce a brief moment of ambiguity before moving on in your new key.

To modulate using pivot chords, you must first identify which chords can work as a pivot. For our example, we will use the keys of C major and G major.

First, write out the chord diagram for each key:

Second, identify which of the chords are the same in both keys:

These are our pivot chords. Any of these can be used to help pivot into the new key.

In the example below, the tonic key is C and the music passes through G and into Em. For the first modulation, the vi chord acts as the pivot chord as it is also chord ii in G. This modulation is never confirmed by a perfect cadence, but there is an imperfect cadence to give balance to the phrase in the second bar. In the third bar, the vi chord (in G) acts as a pivot into Em, where it is also chord I. We then get a final perfect cadence in our new key of E minor. 

If we were to move directly from C to Em, we could use either C, Em, G or Am to pivot into a new key, but it would be less subtle as the two keys are more distant. Using a passing modulation is less abrupt and paves the way for more complex use of passing modulations should you wish to spice up your harmony later on!

Phrase 1:

Accidentals

As seen here, our first phrase contains the two flats from the key signature and no other accidentals. This would leave us with the option of either Bb major or G minor.

Presence of tonic/dominant notes

In Bb, we would need at least the Bb (tonic) to prove our key. Here it is used quite regularly, however we also begin the piece on a G. This would suggest G minor, but we do not have an F# leading note in the melody to prove it conclusively and therefore it is up to us.

Cadence patterns: if we look at our cadence (marked by a fermata in our example), the melody falls stepwise onto an A. In our two possible keys:

• Bb: An A is present in chord iii, chord V and chord vii. As only chord V could fit a cadence, we would have to harmonise this cadence point with an imperfect cadence in Bb.
• Gm: An A is present in chord ii, chord V, and chord vii. Again here, we would have to use an imperfect cadence with chord V.

The preference here would therefore be Gm, as it would give us a solid beginning to our harmony with an opening G. It also gives us an imperfect cadence with the 2^nd degree of the scale in the melody – much more convincing than falling onto a leading note in the major key.

Phrase 2:

Here, it is relatively straightforward. Following from phrase 1, there are no accidentals to suggest a new key, and a 2-1 melody falling onto the tonic of Gm at the cadence, suggesting a strong perfect cadence.

Phrase 3:

Here, we hit our first modulation. The immediate giveaway is that the cadence point ends on a Bb, matching a 2-2-1 perfect cadence pattern in Bb major. There are no other suggestions here that anything changes. In fact, we could stay in Gm if we wanted, but then we would be missing out on variety, and after all variety is the spice of life (and, evidently, chorales…). 

In our planning, we now know that we need Phrase 3 to move from Gm to Bb major in time for a perfect cadence.

 

Phrase 4:

Phrase 4 brings around more obvious change: A B natural at a cadence leading up to C. This could suggest C major or C minor, and a quick glance at our related keys would suggest Cm as the best key.

This presents a challenge: how to reach Cm from Bb major. You would either have to move through Eb or Gm and then continue on to modulate a second time to Cm. We will come on to how to modulate after we conclude our planning.

Phrase 5:

Our 5^th and final phrase ends on a G, and as with most modulating pieces this would suggest a return to the tonic key of Gm. The return of the Bb provides further evidence that this is the case.

Overview of our Modulation Plan: 

During our planning and identifying keys, we have decided that the following scheme will be applied to our melody:

• Phrase 1 – Gm.
• Phrase 2 – Gm.
• Phrase 3 – modulate to Bb.
• Phrase 4 – modulate to Cm.
• Phrase 5 – modulate to Gm.

Extending Your Plan with Passing Modulations

Of course, we do not have to stay in G minor completely for our first two phrases. We can use passing modulation to dip in and out of any number of related keys and borrow chords from them in order to add even more excitement to our harmony! The opening of phrase 2 for example would sit perfectly happily in D minor (our dominant key) for the first three crotchets before returning (via our lovely pivot chords, of course) to G minor. 

There are infinite possibilities – have fun with it!

Summary

You should now be able to identify keys and key changes within a standard chorale melody. Note that I am only covering major and minor key chorales in this introduction, in the name of relative simplicity! Perhaps another day…

This lesson leads on to Lesson 8: Suspensions. Make sure you are familiar with the material here before you move on.