Some chord progressions are so distinctive that they practically dictate the melody. A good example for me is Something by George Harrison:
Other progressions form a foundation for any number of melodies. On the Hook Theory Blog, they analysed the chords of 1300 popular songs for patterns. The chord sequence that appeared the most often was this:
I V vi IV
or, in the key of C,
C G Am F
Some examples of this progression include Let it Be by the Beatles or Edge of Glory by Lady Gaga. There are probably thousands more.
More often than not, the progression of chords gives little idea of what the finished piece might sound like. All sorts of melodies and treatments can be built upon a common base. It’s very unusual for a composer to devise a completely original chord sequence and, in fact, whole genres can be built upon an established sequence – the best example being the 12-bar blues.
I had a go at testing this out. I started with this simple sequence:
G D | Em | C | D7 | G D | Em | A7 | D7 | G | G7 | C | Cm | Cm | G | Em | Am | D6 | G.
This is a pretty standard 16 bar progression, with a hold for an extra bar on the Cm. This is what it sounds like played on piano and acoustic guitar:
I composed two different melodies for this progression. My first example sticks to these chords rigidly. It’s called That’s the Way it Starts:
I moved on to a second example. This was much harder than I expected, because it’s really hard to get the first melody out of your head while you’re working on the second one. In the end I had to leave it a few weeks before coming back to it.
I ended up with a much lusher ballad called Every Woman Every Man. I took the liberty of enriching the chords:
Intro / finish: Gmaj7 | Em7 | Am7 | D9 D7
Verse: Gmaj7 | Em7 | Cmaj9 | D9 | Gmaj7 | Em7 | Am7 | D9 (repeated)
Chorus: Gmaj7 | G7 | C | Cm7 | Cm6 | Gmaj7 | Em7 | Am7 | D6
I hope you’ll agree that the two examples do sound quite different, not in terms of the overall style and arrangement, which pretty well stays common, but certainly in the melodies. If you added lyrics to the two pieces and then used different singers, musicians and arrangements, perhaps even working in contrasting genres, you’d be hard-pressed to detect the same progressions.
I’m not sure this counts as a proper experiment because I never really managed to isolate a single variable, in this case the chord progression, in order to study its effect cleanly. But it was an interesting experience. I found it a bit like pilates, if you’ve ever tried that, in which the whole skill is to isolate movements, such as moving one leg without moving the other. As with most things in life, with enough practice you can get there.
