Reharmonisation Part 3: Standard Substitutions 1

As mentioned before, this tutorial series is structured in a way that we start with the easy (yet effective) strategies and work our way up to the really deep reharmonisations.

After we had a look at the power of changing bass notes of chords to non-root notes in the last part of this series, in this part, we will focus on the diatonic standard substitutions.

This means, we will not yet leave the space where we source our material from chords that are not part of the current diatonic key but try to qualify the existing 7 functions. I'm pretty sure that most of you are aware of the principle that is discussed in this part but I will try to present these things in context and how they make sense in a "film music esthetic's" approach.

The diatonic space of a major scale is filled with these chords (in this case of C major)

While we effectively have 7 different chords here, from a functional point of view, we only have 3. There's the tonic of C, the subdominant of F and the Dominant of G. These are the three pillars of diatonic harmony for the last few centuries. You will be able to harmonize any diatonic melody with just these three chords (mostly even just Tonic and Dominant are enough) in a way that makes musical sense.

Take this relatively random diatonic melody:

https://soundcloud.com/robin-hoffmann/harmonisation-i-v-i/s-6S2xnzSkX17

As you can see, I'm using a subdominant in the last bar, but theoretically could sustain the dominant over that f as well. All the other bars using Tonic/Dominant. I'm using a G7 instead of a straight forward G to create a bit more dominant tension (and to make a few more harmonisations plausible).

Of course, we can also "extend" using the subdominant more:

https://soundcloud.com/robin-hoffmann/harmonisation-i-iv-v/s-QeWwQz6y3qT

There are quite a few possibilities how one could harmonise this melody with these three chords.

Let's talk about the fundamental strategy to reharmonise.

In a nutshell, you look at the melody notes you want to be covered by one chord and find a chord that includes these notes. If we limit ourselves to the three chords we were just talking about, we could for instance look at beat 3 in bar 1 which is an F in the melody. This could for instance be the root of the Subdominant or the 7th of the Dominant. Any G could be the root of the Dominant or the fifth of the Tonic etc. etc. The more melody notes you need to cover with one chord, the more limited your possibilities will be. 

If we take into account the notes included in the Tonic chord (C, E and G) and the ones in the Dominant7 chord (G, B, D, F) we pretty much cover alot of ground of our diatonic scale material. We're only missing A which we could make work with the Tonic or Dominant as well (if we extend beyond the basic chord tones) or we just use the subdominant.

While from a melodic micro cosmos we could get away with the strategy to simply look at melody notes and assign a chord that has them, in the larger structure that often doesn't create the greatest results.

Let's for instance again focus on the last bar where the melody goes f-g-c. As I said above, I could harmonize f and g with the dominant and c with the tonic. But as I hardly get around using the dominant in the second half of the previous bar, I would be stuck on it for quite a while. The melody however does a very strong IV-V-I motion which of course works also harmonically by underlaying these chords. (From a classical standpoint, the voice leading is completely illegal as the bass notes move in octave parallels with the melody which is a HUGE no no but this is a subject for another article - but taking this into consideration, sustaining for longer on the Dominant and taking the melody F as its 7th would be the "more correct" yet harmonically more boring variant).

So far so good. We've managed to lay the groundwork for harmonisation. Of course none of that does sound even remotely like film music, more like a children's tune but we'll get there, I promise.

So now, let's address the elephant in the room which we ignored for a while. Above I said, in spite of having 7 diatonic chords available, we only have 3 harmoic functions available which we discussed now. But what about the remaining 4 chords? Let's have a look at them again:

I said above that when you harmonise something, you look at the melody notes you have and which chord contains them. If we now look at the 4 chords that we ignored until now, we see that big parts of their structure (= 2 of their 3 notes) are the same as we have already in our "core functions" of tonic, dominant and subdominant.

For instance, the Dm (D-F-A) has a lot of Subdominant quality of F major in it (overlapping F and A), Em has the E and G from the Tonic, Am has the C and E from the Tonic, and even that odd Bdim looks like it is just missing a G to become a fully grown G7 chord.

So in a way, these 4 chords are "slightly different" alternatives to the three core functions. And this is where their reharmonisation potential lies.

Let's finally take the turn to film music. James Horner's strikingly simple yet excellent score for Apollo 13 contains a choral that you can hear in the beginning of this track. We can only speculate about Horner's motivation behind this part, but for me this quasi religioso choral part has a really strong emotional impact, almost like preparing to "rise up to the sky" if you want to stretch this religious analogy.

It looks something like this:

https://soundcloud.com/robin-hoffmann/apollo-13-original/s-5lBLhtldwsP

For our purpose, let's get this back to C major and reduce the harmonisation to the core functions:

https://soundcloud.com/robin-hoffmann/apollo-13-reduced/s-hSqRnlFlGlk

Now, as I mentioned above the four "non core" functions are alternatives for the core functions and (as long as the melody note(s) permit(s)) can very easily stand in for them without changing a lot of the musical course of the harmonic progression.

So let's take this chorale and try out what happens if we replace all Cmajor chords that are not opening or closing a progression (as you would want to keep them intact) with the 6th degree of Am which is a common "stand-in" for the tonic. Of course, we can only do that on melody notes of C and E that overlap in both chords:

https://soundcloud.com/robin-hoffmann/apollo-13-am-replacement/s-vUebIDuZVVM

Doesn't seem to be making a huge structural difference but sounds a little bit more interesting. (in spite of the parallels)

Let's try replacing C major by Em:

https://soundcloud.com/robin-hoffmann/apollo-13-em-replacement/s-0uN0s69xMW3

Again, parallels between F and Em but other than that not too bad either. Let's try counteracting these parallels by replacing the F chord by Dm which is a useful alternative.

https://soundcloud.com/robin-hoffmann/apollo-13-dm-replacement/s-8o3Oyy57w9q

That works pretty well, too. I could go on and on trying out different things here. The essence to take away is, that it seems like these diatonic "replacements" don't change much about how the music feels or how the harmonic path is structured.

So these standard substitutions are pretty much functionally identical, yet provide a bit more colour.

Let's go back to Horner's original and have a look what he did:

https://soundcloud.com/robin-hoffmann/apollo-13-original/s-5lBLhtldwsP

He seems to be using similar strategies to create harmonic variants:

Beat 2 in bar 2 and 6 is harmonized with an F (I) and Am (iv), on beat 3 of these bars he changes the bass note (see last part of this series). In the further pass of this sequence in the score he keeps replacing chords with other diatonic standard replacements.

Again, this is an incredibly simple reharmonsation strategy which in the right context can create a lot of harmonic impact as seen in this cue. Just being aware that you can replace "core functions" by "secondary functions" will allow you to create interesting harmonic progressions without even leaving the diatonic space.

If you now combine this principle with the one explained in the last part, where you use alternative bass notes, you can create incredibly captivating chord progressions in the very limited space of a diatonic scale.