Introduction
Jazz is generally homophonic. This means it consists of:
- Harmony (Chords); and
- Melody (Improvisation)
When ‘comping or playing a chord progression, you have to take account of three things:
- The chord itself – notes that make up the chord;
- The chord voicing – the order of and interval between notes;
- Voice leading – transition between chords.
We have already discussed ‘Chord Voicing Rules’ in a previous lesson where we covered the first two points – that is, how to build Jazz chords and some general rules about how to create a nice sounding voicing. So this lesson will focus on the final point – that is, how to transition between chords, or voice leading.
Melodic Motion
But before we discuss voice leading, we need to learn the four types of melodic motion. If two melody lines are playing simultaneously, there are four ways they can move:
- Parallel – two voices move in the same direction by the same intervals
- Similar – two voices move in the same direction by different intervals
- Oblique (Pedal Point) – one voice stands still while the other ascends or descends
- Contrary – two voices move in opposite directions
Voice Leading
Every chord progression has two dimensions: horizontal and vertical. Let’s just take a II-V-I in C, so:
Dm7 | G7 | CMaj7 ||
- Vertical = thinking of a chord progression as a series of chords: Dm7 | G7 | CMaj7 ||
- Horizontal = thinking of a chord progression as four independent musical instruments or ‘voices’ in a choir, each of which plays only one note per chord (Bass, Tenor, Alto, Soprano). So we have four different melodies which add up to make each chord.
Our goal in playing a chord progression is to play the chords in an interesting and smooth way. So we ‘lead’ each ‘voice’ smoothly from chord to chord. If we, again, play a II-V-I in C, we could play it like this:
| Voice | Dm7 | G7 | CMaj7 |
|---|---|---|---|
| Soprano | C | B | B |
| Alto | A | G | G |
| Tenor | F | F | E |
| Bass | D | D | C |
The general principles of voice leading in Jazz are the same as in Classical Music. But Classical Music is a little bit stricter than Jazz, and has some superfluous rules or guidelines that we don’t adhered to in Jazz. For example, when voicing chords in Classical Music you would try to:
- Avoid parallel 5ths or 8avs
- Avoid crossing voices
- Avoid all the voices moving in the same direction (similar motion)
- Have the leading tone resolve to the tonic
In Jazz, we don’t have as many strict rules, and in fact it can sound better if you break these rules. For example, Parallelism in chords (all the voices moving in parallel motion) can actually sound quite nice and Jazzy, especially in genres that use non-functional chord progressions like Post-bop or Modal Jazz. This is generally avoided in Classical Music, but in Jazz it’s perfectly fine and actually encouraged.
Voice Leading Rules
There are, nevertheless, some voice leading principles which you should try generally to adhere to even in Jazz. These are:
- Outer-voice counterpoint
- The law of conservation of energy
Outer-Voice Counterpoint
The outer voices are the highest (soprano) and lowest (bass) notes in a chord voicing. These are the two voices that are most clearly hear in a chord. You can always hear the top note and bottom note clearly, with the middle being a bit harder to distinguish.
(Aside: That’s why when you’re transcribing chords from a recording you should always start with the highest and lowest note of each chord).
The following are some guidelines to follow (and break when necessary) when voicing chords:
- Soprano and Bass voices should be melodically interesting and generally move by step – when comping or playing chords, the top and bottom notes of your chords should create an interesting countermelody to the actual melody.
- Soprano and Bass voices move in contrary or oblique motion (including pedal points) – Using contrary and oblique motion sounds like the voices are independent, whereas using similar motion sounds like you’ve ‘thickened’ or ‘harmonised’ a single melodic line. But definitely don’t avoid parallelism just for the sake of some rule. In some contexts parallel chord movements sound very jazzy.
- The chord will sound harmonically stronger if the Soprano and Bass emphasise the tonality and quality of the chord – by playing either the root in the bass and the Guide Tones (3rd or 7th) in the soprano. However this can be a bit plain when overused.
- Create Guide Tone Lines – where one voice sings the Guide Tones of each chord
Law of conservation of energy
- Lines should be smooth and independent and melodically interesting.
- Voices should retain as many common tones as possible. For example, the chords Dm7 and G7 both have the notes D & F; therefore these two notes should (generally) not move when transitioning from Dm7 to G7.
- All voices that move should do so by as small a distance as possible and avoid leaps (except the bass which can jump by a 5th or a 3rd and still sound good).
Putting it all together
And that’s it. So whether you’re ‘comping in a band or just accompanying yourself, there’s only few things you need to take account of when playing the chord progression:
- Voice the chords nicely; and
- Use the above voice leading rules when transitioning between chords
If you do this you will create a really nice and jazzy sounding harmony.
And here’s a voice leading exercise for you: