This post is one of a 2-part series of free basic music theory lessons on my blog, musictheoryde-mystified.com. You can see the complete list here. Please feel welcome to make a comment or ask a question.
The relationship between two keys is simply how many notes they have in common: the more notes in common, the closer their relationship.
Why do we care? Because this is not just true on paper. Theory reflects reality. Closely related keys actually sound close, musically. They sound compatible.
In the preceding lessons we have already seen two types of key relationships; the cycle of fifths and relative major and minor. Here’s a quick review:
The Cycle Of Fifths
The cycle of fifths is a list of the keys in the order of their key signatures, from every note being a flat through to every note being a sharp. In this list, any two adjacent keys have all but one note in common.
The effect of this close relationship is that the music can comfortably and cohesively shift from one key to the other and back.
This is most easily demonstrated with chords. We’ll look at chords in a later post, but for now we can say that a (basic) chord represents a key. Chord names mimic key names, just in a shortened form. A note name by itself implies a major chord/key. If it’s followed by ”m”, it’s a minor chord.
Adjacent keys in the cycle of 5ths can be visited in any order. Here’s a short example in C major with a simple melody and chords. As usual in my posts, the examples are purely for illustration, so they don’t sound as exciting as real compositions…
Here’s an example of a simple melody in C major visiting adjacent keys, as represented here by chords.
A large proportion of music in Western culture in most genres, whether fast or slow, rhythmic or free, accompanied or solo, is based on visiting closely related keys.
- To find the next key in the cycle of 5ths, go up to the 5th letter in the key to find the root note, then sharpen the 7th note of the scale (add a sharp or lose a flat).
- To find the previous key in the cycle of 5ths, go down to the 5th letter in the key (or up to the 4th letter) to find the root note, then flatten the 4th note of the scale (add a flat or lose a sharp).
You can also use the cycle of 5ths as a list to look up the root note of a key and its latest sharp or flat, or even the complete key signature. An example of this for major scales can be found in 12. Major Keys And The Cycle/Circle Of Fifths. The cycle of 5th for major and minor keys, with key signatures, is shown in The Cycle (circle) of Fifths.
Relative Major And Minor
Next we looked at another close relationship between keys, one where two keys have every note in common: relative major and minor. Having all notes in common, the difference is in which one is the root note. Of course, changing the root note changes the mode, hence the term relative major and minor.
Major and minor have different characters – different tonalities. Moving between one and the other feels a bit like going to an unfamiliar corner of a familiar room; like viewing the scene from a different angle.
Here is a simple melody in C major visiting the relative minor.
- To find the relative minor of a major key, go up to the 3rd letter in the key and keep the same key signature (play the same notes starting on the 3rd note).
- To find the relative major of a minor key, go down to the 3rd letter in the key and keep the same key signature.
For more on relative major and minor, please visit 13. Relative Major And Minor.
Parallel Major And Minor
There is a third type of key relationship which we haven’t yet visited; parallel major and minor. This means a major and a minor on the same root note.
The easiest way to see their relationship is by writing one on top of the other, literally parallel.
Here’s an example on C:
In the above graphic we can see that the parallel minor has three notes that are flattened compared to the parallel major, the 3rd, 6th and 7th notes.
Key signature wise, the parallel minor is 3 keys behind the parallel major (anticlockwise).
Parallel major and minor have only four of their seven notes in common so, as far as the cycle of 5ths goes, they’re not that closely related. However, because they share the same root note, their relationship feels closer than that.
Here is a simple melody in C major visiting the parallel minor.
Another Shortcut
Here’s another way to remember a few keys you don’t know…
Major to Parallel Minor
- If you know the key signature of a major key then the minor on the same root note, the parallel minor, is 3 keys backward (anticlockwise) in the cycle of 5ths.
- If you know the notes in the scale rather than the key signature, such as when playing by ear, flatten the 3rd, 6th and 7th notes. You’ll get the same result.
Minor to Parallel Major
- If you know the key signature of a minor key, the major on the same root note is 3 keys forward (clockwise) in the cycle of 5ths.
- If you know the notes in the scale, sharpen the 3rd, 6th and 7th notes.
Examples
Major to parallel minor
We know C major has no sharps or flats, so C minor has 3 flats (Bb, Eb, Ab)
Minor to parallel major
We know A minor has no sharps or flats, so A major has 3 sharps (F#, C#, G#)
Nothing In Common Is Still Something
On the far side of the relationship spectrum, two keys can have no notes in common. This is achieved by sharpening or flattening the root note and thus, every note. Musically, it’s a complete reset. Moving between two such unrelated keys can sound anywhere from refreshing to dramatic or mysterious.
In the case of C major, 0 sharps/flats, sharpening everything gives us C# major, 7 sharps.
Similarly, flattening everything gives us Cb major, 7 flats.
- To sharpen everything, go forward (clockwise) 7 keys in the cycle of 5ths. All flats become naturals and all naturals become sharps. Every note is played 1 semitone higher than before.
- To flatten everything, go backward (anticlockwise) 7 keys in the cycle of 5ths. All sharps become naturals and all naturals become flats. Every note is played 1 semitone lower than before.
Note: there is a practical limit to how many sharps or flats we can have. If there are more than 7, one or more notes in the scale will have a double sharp or double flat. These exist but are only used when necessary, usually as an accidental rather than as part of a key signature. For keys, it’s generally easier to respell (rename) the root note and avoid the issue.
- If there are more than 7 sharps or flats, respell the root note. The key signature will go from lots of sharps to a few flats or from lots of flats to a few sharps.
For example, you probably remember by now that G major has 1 sharp, F#.
- If we sharpen everything we get G# major, with 8 sharps. All the naturals are sharps and F is a double sharp.
- However, G# is the same pitch as Ab. Ab major only has 4 flats so it’s much easier to read and doesn’t require a double anything.
- Knowing G major does help you find Gb major though. By flattening everything we go from 1 sharp to 6 flats, no doubles there.
From The Known To The Unknown
Use your knowledge of key relationships to help learn the key signatures of more keys. Start with a couple of common or easy to remember keys and with a little thought, you’ll soon know most of them. At the same time you’ll become more familiar with the idea of keys being related to each other.
- For instance, just by knowing C major (0 sharps/flats) you can quickly find its parallel minor, C minor (3 flats), 3 keys back in the cycle of fifths or flatten the 3rd, 6th and 7th notes.
- You can also find C# major and Cb major by sharpening or flattening everything, as we’ve seen above.
- From C minor you can find C# minor (sharpen everything: 3 flats becomes 4 sharps). Or you can find C# minor from C# major using parallel major to minor.
- From C minor you can also find Eb major (still 3 flats), using relative minor to major (count up to the 3rd note in the key).
- Similarly, from C# minor, using relative minor to major, you can find E major (4 sharps). Or you can find E major by sharpening everything in Eb Major (3 flats becomes 4 sharps).
- We know A minor already, but if you forgot, you could find that from C major using relative major to minor (count down to the 3rd scale note, keeping the same key signature, 0 sharps/flats).
That’s 8 keys and key signatures just from remembering one key!
And I could keep going: From E major you can find E minor and so on… Not to mention using the cycle of 5ths to find the next key (add 1 sharp or lose 1 flat) or previous key (add 1 flat or lose 1 sharp), and then their relative minors or majors, etc.
Try this yourself with another common key like A minor or G major.
Try These…
Test your ability to think in key relationships! Name the following keys and list either their notes as a scale or their key signatures:
- A major has 3 sharps; F#, C#, G#. What is the next key in the cycle of fifths after A major?
- Bb major has 2 flats; Bb, Eb. What is the previous key in the cycle of fifths before Bb major?
- D major has 2 sharps; F#, C#. What is the relative minor of D major?
- D minor has 1 flat; Bb. What is the relative major of D minor?
- E major has 4 sharps; F#, C#, G#, D#. What is the parallel minor of E major?
- F# minor has 3 sharps; F#, C#, G#. What is the parallel major of F# minor?
- You worked out the key of D minor. Now sharpen it.
- G major gas 1 sharp; F#. What is the key of Gb major?
Answers at the end of this post.
Key Relationships Are Real
Being able to work out key signatures by using the various key relationships not only helps you with the odd unfamiliar key but it also reinforces your understanding of these relationships. As mentioned earlier, key relationships aren’t just musical arithmetic, they are real: when listening, you can hear the connection between related keys.
Try This…
For any key, the next and previous keys in the cycle of 5ths and their relative minors or majors are the most closely related. Choose a key whose key signature (or scale notes) you remember and work out these closely related keys.
If you play chords, try changing between the chords of these keys. If you play melodies, play their scales or triads. Either way, you’ll find that you can mix them up into any order and they will feel like they belong together.
(Sib simple chord sequence as chords, then triads, then as rapid scales)
You can also use closely related keys to work your way progressively to a distant key without really noticing, such as in the classic chord progression of Jimmy Hendrix’s Hey Joe, a cascading sequence of forward steps in the cycle of 5ths. In that song, the surprise comes when the sequence resets at the start of the next line: only then can you hear how far from home you ended up…
(Sib Hey Joe progression in scales and chords with repeat)
Note: we’ll investigate chords and triads later in this course.
If you play by ear, you can use any of the methods above to find how to play the scales of related keys. All you need to remember is the name of the key.
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Answers to Try These…
- E major (latest sharp is D#). 4 sharps; F#, C#, G#, D#
- F major (latest flat is Bb). 1 flat; Bb
- B minor: same key signature, 2 sharps; F#, C#
- F major: same key signature, 1 flat; Bb
- E minor: 1 sharp; F#
- F# major: 6 sharps; F#, C#, G#, D#, A#, E#
- D# minor: scale = D# E# F# G# A# B C# D#. 6 sharps; F#, C#, G#, D#, A#, E#
- Gb major has 6 flats: scale = Gb Ab Bb Cb Db Eb F Gb. 6 flats; Bb, Eb, Ab, Db, Gb, Cb