>Step by step

Exploring chord progressions based on modal harmony

1 To get our heads around modal harmony, we first need to understand exactly what a mode is. Let’s have a refresher: here’s the C major scale, played from C to Con the white notes of the keyboard–C DE F GA Band C. The particular pattern of intervals between the notes that make this a major scale is known as the first mode – the Ionian mode.

2 If we were to play this scale from a different starting note – eg, D to D – the pattern of intervals would be different, resulting in a different-sounding scale or mode. This second mode is called the Dorian mode. What you end up with is effectively a natural minor scale with a raised sixth. Because we’ve started on the note D, this scale is D Dorian.

3 Here’s a diagram of the seven modern modes and their names: Ionian (aka Major), Dorian, Phrygian, Lydian, Mixolydian, Aeolian (aka Minor), Locrian. It describes the notes in each mode when played from a C root note, clearly showing the different patterns of intervals between the notes that give each mode its own characteristic sound. 4 There’s no harmonic function in modal music, so one of the main rules to bear in mind is that you can’t use a dominant chord to establish the tonic like you can in tonal music. For a tune to have that definitive ‘modal’ sound, creating a specific sort of floating, disconnected ambience, the dominant-tonic resolution, aka V-I cadence, is a big no-no.

5 There are other techniques that can be used to infer the tonal centre. For example, you can repeat the mode’s root note to ‘bend the ear’ towards accepting that as the tonal centre. If you’re in C Dorian, say, and want to establish C as the tonal centre, make sure the bassline or left hand part is centred on that note, as shown here.

6 With the tonal centre now indicated by a persistent, repeated root note in the bass, we can reinforce the modal nature of the tune using a technique known as alternating triads. This means playing two adjacent triads over the mode’s root note, with a melody containing notes from the mode over the top. But how do we know which chords to play?

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To find out, we first have to work out the source scale for the mode we’re using as the key. Each of the seven modes is derived by playing a major scale from a note other than its root, so which one is C Dorian derived from? Since Dorian is the second mode, we need to find the major scale that has the note C as its second

Bb Bb Eb Bb). degree: major ( C D FGA

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The two triads we need will be the two major chords built off the fourth and fifth notes in the source scale. So if Bb this scale is major, the two chords are Ebmaj Eb- Bb) IV – ( G- and V – Fmaj (F-A-C). Between them, these contain six of the Bb seven notes in the major scale, making them the most likely pair of triads to work in this mode.

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Bb Since C Dorian is the major scale Bb Bb, played from C to C instead of to we can use these two triads to harmonise most of its notes. The note that doesn’t fit – D in this case – will most likely fit the parent Bbmaj. scale’s I chord – So here’s our C Dorian example with its repeated C in the bass, Eb alternating and F major triads, and the same C Dorian melody over the top.

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The table above shows all of the source scales, IV chords and V chords you’d need to use the alternating triads technique in all seven modes based on the root note of C. When you compare the different modes using the same root note like this, it really highlights the distinct feel and sonic character of each one.

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So, we’ve seen that you can make modal tunes out of chords built using tertian harmony – notes stacked up in third intervals. It sounds more modal, however, if you use quartal chords – notes are stacked in fourth intervals. Here’s the set of quartal triads diatonic to C Dorian – all note pitches stacked in fourths, taken from the notes in the C Dorian mode.

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This final version of our example tune uses the same bass and synth melody, but this time with quartal chords over that C bass. Of the diatonic quartal triads available, we’ve used the V (G-C-F)

Bb-Eb) and IV (F- chords in an alternating pattern, as shown. Strictly speaking, the chords would be labelled Fsus2/C and Ebsus2/

C respectively.