Hello there! Ever played or heard two songs and noticed they were melodically similar, despite sharing no 'common' chords? Well, the good thing is that you're not crazy. The chords don't need to be the same in order for two songs to sound identical, only their relationship.
So let's turn our attention to the chord progression of two songs. The first being the dainty little ukulele song 'I'm yours' by Jason Mraz and the second, 'Hey Soul Sister' by Train.
Notice anything? The progression is exactly is the same. Even though the tempo and vocal melodies may be different, the songs share an identical chordal relationship. That's why they sound similar.
Now before your mind takes you on a surrealist journey, picturing abstract chords holding hands and courting another, what we mean by that is the musical, intervalic relationship within Western music. Enter the Circle of Fifths.
The Circle of Fifths is a visual representation of all the notes in the chromatic scale and their respective key signatures, laid out in an ergonomic fashion for us to see how they correlate with one another. The origins of the circle lie with Pythagoras, the titan of ancient scholarship most notable for his mathematical theoreom. In the 6th century B.C, having already discovered pitch frequencies and tuning he devised the Pythagorean Circle to help visualise the relation between the various keys.
Behold. The circle in all of its glory. The 12 notes are spread out around it like the numbers on a clock. Each point is the 5th of pitch before it; looking at the top of the circle we see that C is followed by it's 5th: G, which is then followed by its 5th; D and so on and so forth.
What does it do?
The Circle of Fifths provides you, at a glance, the amount of sharps and flats in any particular key signature. Every song has a key signature, and the ability to detect this is vital in both reading and writing music. Starting at the top of the diagram, C, we have no sharps or flats. Visualised on a piano, this means you'll meet no black keys as you ascend through the scale. Moving clockwise around the Circle of Fifths, each key includes one more sharp than its predecessor. For example, the key of G has one sharp, the key of D has two sharps, and so on. For flats, we simply work anti-clockwise from the top of the diagram. As we descend in fourths, we add one flat for every point around the circle. The key of F has one flat, the key of Bb has two flats, etc.
Why do I need it?
Why is this useful? Well, it makes transposition considerably easier. You may need to transpose music so that it better suits certain instruments. Let's suppose you have a piece of sheet music originally written for the flute (a concert pitch instrument) which you now have to play on a transposing instrument such as a clarinet. Because of the very nature of the instruments involved, a C note on a clarinet will sound more like a Bb. As a result, you'll need to transpose all those notes by the same interval. A quick glance at the Circle of Fifths allows us to identify how far up or down in tone the piece would need to be transposed in order for the new instrument to sound the same as the original pitch.
For ukuleles, the diagram allows us to quickly shift around different keys. Let's take the ubiquitious four chord song, the happy I-V-vi-IV that we all cherish. For example's sake, we're playing it in C with the chord progression C – G – Am – F. Say now, that we have a fussy lead singer who's feeling particularly erratic and demands that we transpose the progression two 'fifths' up into the key of D. We need only throw a look at the Circle of Fifths to figure out how best to do this.
C becomes D, G becomes A, Am becomes Bm, F becomes G.
With Ukulele Toolkit, just select key of D, all chords will be transposed from the key of C (as shown in left) to the key of D (in right).
This 'step' in music, i.e moving up a whole tone, can also be used as a harmonically rousing key change. It has been employed in countless songs, normally to generate real excitement and climax.
Remember that the relationship between the chords remains the same, and only the chords 'holding' the place in the progression, so to speak, are moved up or down.
This also lends itself fabulously to transcription, whereby one commonly notates the bass line of the music first before adding the chords and melody. Having a solid grasp of the Circle of Fifths allows you to relate the key signature to everything else in the music.
Now let's transpose both Chord Sets to the key of C.
Once transposed into the same key, we can see that both songs truly share the same chordal relationship.
So there we have it. Obviously we're just skimming the surface here. Music theory goes very technical and we wouldn't want to confuse you at this point. If you'd like to read wider on the Circle of Fifths and the nature of music theory, we'd strongly suggest the following posts:
We'd also encourage you to test the veracity of the Circle of Fifths for yourself. Switch on any music channel showing popular music videos, or alternatively, google the current Billboard Top 100. Sit down and see how many of these songs use the same chordal relationship, even if the key, genre, or instrumentation may be wildly different. It's one of the industry's worst kept secrets how strikingly similar pop songs are. Some have even made academic endeavours to find out certain 'formulas' of pop music. If you're interested, we recommend reading the following article: http://www.hooktheory.com/blog/chord-progression-search-patterns-and-trends/