Reharmonization. It’s kind of a funny word when you first encounter it. It means exactly what it sounds like. To reharmonize something is to alter the harmony, and when we talk about harmony we’re really talking about chords. So to put it plainly, to reharmonize something is to change the chords. Why would a musician want to change the chords to a song? And why not change the melody, too? And most importantly, how does one go about changing the chords to a song? Can you just choose any chords you like when reharmonizing? In this article we’ll answer all of those questions – and more.
First things first – let’s discuss why we do NOT alter the melody, and instead concern ourselves with only the harmony. The melody is the most recognizable part of the song, the part that the listener walks away humming. Changing the melody of a song is really changing the actual song, so we tend to leave the melody alone. But changing the harmony can allow us to drastically affect the sound of the song without actually changing the melody. This allows the listener to hear the same melody they are already familiar with in a fresh, innovative way. “Reharming” a song (short for reharmonization) can create an entirely new mood and character, and this is a very powerful and creative skill for musicians to have. Orchestrators, composers, and arrangers all practice the skill of reharmonization regularly.
Reharm is a very dense topic, and can be a very advanced skill. But it just takes a little bit of practice to start developing some reharm tools. Let’s start with a very simple song that we all know – “Happy Birthday.”
Notice how simple the chord changes are – F major and C major, which in the key of F represent the ‘I' and 'V’ chords.
We're going to alter the chords - meaning we may change some, remove some, or add some. We are not going to do anything to the melody. Let's start with an easy one: in measure 2 and 3 we have a 'C' major chord. We can change this to a C7 chord in measure 3, which will act as a 'V7' chord going to 'I' (the 'F' major chord) in measure 4.
Ok, now let's add another chord to this progression. It's very common in jazz to precede 'V' chords with a 'ii' chord, creating a 'ii - V - I' progression. Since we have the 'V7' chord in measure 3 we can precede it with the 'ii' chord, which would be G minor.
Lastly, we'll reharm the resolution of this 'ii - V' progression. Instead of playing Gm7 to C7 to F major, we're going to play Gm7 to C7 to D minor 7 (sometimes referred to as a "backdoor ii - V"). Why does this work? Look at the notes that F major and D minor have in common, and remember, too, that D minor is the relative minor of F major.
Now listen to the original and the reharmonized version: