Modulation describes the process where a piece of music changes from one key to another key.
When you start writing a piece of music one of the first things you do is choose a key to compose in. This choice of key determines the scale you use, how many sharps and flats there are and what chords you can use. This key is sometimes called the “home key”.
Many songs and pieces remain in this home key and do not change. However, to make a piece more interesting a composer may choose to change into a different key at some point during the piece. This change is called a modulation.
There are lots of different ways of modulating, but we are going to have a look at 2 of the most common ways you will come across:
Pivot Chord or Common-chord Modulation
The advantage of pivot chord modulation is that it enables a smooth change from one key to another. It does this by using a pivot chord.
A pivot chord is a chord that belongs to both the home key and the the key the music is changing to.
Let’s look at an example:
Imagine we are wanting to write a piece of music in G major.
We could use the primary chords of G major (I, IV, V) which are the chords G, C, D.
Now imagine we would like to modulate to D major.
The primary chords in D major are D, G, A.
Can you see that chord V in G major (D) is the same as chord I in D major (D)?
This means we could use the chord D as a pivot chord to modulate from G major to D major.
Can you also see that chord I in G major (G) is the same as chord IV in D major (G)?
This means that we have a choice of 2 pivot chords that we could use.
Have a look/listen to the following piece which modulates from G major to D major:
This technique of pivot chord modulation works best if you move to closely related keys (keys that only have a few sharps/flats different from each other).
Closely Related Keys
Phrase Modulation/Abrupt Modulation
The 2nd type of modulation we are going to have a look at is Phrase Modulation or Abrupt Modulation.
This modulation is a sudden change of key.
No pivot chord is used.
A Phrase Modulation often involves a key change that goes up by a semitone or a tone. You will hear it in lots of pop songs as the key changes for the last verse or chorus to create and exciting ending to the song.
Have a listen to this example from The Backstreet Boys’ song “I want it that way”.
The song starts in A major. Listen to how there is a sudden key change up a tone to B major for the last chorus of the song (2 mins 32 seconds into the video).
How to spot a modulation
Modulations can be spotted by listening and looking:
Abrupt Modulations can be easy to hear (like the Backstreet Boys’ track above). They are sudden and not designed to be subtle!
However, pivot chord modulations can be harder to spot. You will be able to spot some pivot chord modulations by listening. However, you may find it easier to spot them by looking at the sheet music.
When a piece of music modulates a composer may write a new key signature – this is a sure sign that the piece has changed key. Also, you will often see accidentals appear (accidentals are sharps or flats written next to a note in the music). However, be careful as these accidentals may also appear if the piece is in a minor key (the seventh note will often have a sharp next to it) or if the music is quite chromatic.
Hopefully this session has helped you understand modulation better.
Now it’s really important you have a go!
- Try improvising on the piano/guitar using the primary chords of G major. Then try modulating from G major to D major using a pivot chord.
- Listen to some music from different styles. Can you hear any modulations? How many pop songs can you find with an abrupt modulation for the final section?
- Have a look at some sheet music. Can you spot any pivot chord modulations?