Confused by Modes?

When I was learning theory at the Guitar Institute, for a while I thought modes were more mysterious than they actually are. So I thought I'd try and shed some light for those of you that are reaching out for new ideas to add to your musical armoury.

At the end of the day, a mode is just a scale that can be used for composing and improvisation. Yes, it does derive from reshuffling another scale, but that is purely a theoretical detail - knowing that doesn't really help know how to use that mode.

In fact, there is a more fundamental concern, known as tone tendency, which has everything to do with how to use any scale for composing and improvisation. We need to get to grips with this.

Major, Harmonic Minor, and Melodic Minor, and the majority of their modes all have one thing in common: the scale contains either a major triad (1, 3, 5) or a minor triad (1, b3, 5) whose root is the first note of the scale. For the remaining notes of the scale, the type of second, fourth, sixth and seventh are determined by which scale we're using. For example, we may have a b7 or a 7. Let's ignore this for a moment, and let's just consider that we want to write a melody. I'll come onto chords a bit later, and then onto dealing with a chord progression.

For now, let's just consider the notes <1, 3, 5> or <1, b3, 5> of the scale. The critical property of these notes is they are stable; they don't cause the listener to want to hear that note move on to another note. The remaining four notes in the scale don't have this property: they are all unstable and create varying strengths of desire in the listener for the unstable note to move next to a stable note. To the listener, these four notes seem to have a tendency to want to move to the nearest stable note.

Major scale and tendency tones

For example, let's look at the major scale <1, 2, 3, 4, 5, 6, 7>. A good way to get a sense of which scale tones are stable, and which are tendency tones, is the following. Play the scale in ascending order from one to seven, followed by any scale note which you hold for a bit. So, you might play the major scale, followed by <1> and listen and see if that tone makes you want to hear it move. Then play the major scale followed by <2>, and so on. Where you feel this final tone needs to move, write this down, and then follow it by a neighbouring scale tone, and see how that makes you feel. Try both its higher pitched neighbour, and its lower pitched neighbour.

For example, nearly everyone feels that <4> is unstable, so we could follow this by <3> (lower neighbour) or <5> (higher neighbour). The majority of people feel that moving from <4> to <3> gives the most sense of stability being reached again.

Once you've established your list and which way you feel the unstable tone wants to move, then try and assess how strongly that tendency is felt compared against the tendencies shown by the other unstable tones in the list. Consensus across many people, musical or otherwise, is that following the major scale by <1>, <3> or <5> is fine - these are all landing notes that don't set up any tendencies. The others are ranked, from least unstable on the left, to most unstable on the right, as <6>, <2>, <4>, <7>. By consensus, <6> needs to be followed by <5>; <2> by <1>; <4> by <3>; and <7> by <1>. So the strongest tendency tone, the most unstable, is <7>. This creates a strong desire within the listener for it to be followed by <1>. We say that <7> should resolve to <1>.

When constructing a melody from the major scale, a lot of the time these tendencies are honoured (for example <7> does resolve to <1> as the next note). This alone is not enough to really create a successful melody that sounds like it is constructed from the major scale based off a given key note. Other factors also apply, such as note repetition, starting the melody on a stable note, ending it on <1>, and so on. This though is material for another lesson.

However, for now, the take aways are: first, a scale has stable and unstable tones, and creating a melody with that scale includes paying attention to resolving these unstable tones. (You don't have to resolve, otherwise we'd be bored stupid, and it's playing games with the listener on this front that can make the melody more memorable). Second, different scale types (including the modes) show different rankings for their unstable tones. For example, <7> in Lydian has much less pull than <7> in Major.

Chromatic tones

Any non-scale tone is rated the same as the most unstable tendency tone of the scale, and its resolution is to the nearest scale tone, preferably the less unstable of its two neighbours. For example, in a major scale melody, b5 would preferably resolve to 5 rather than 4.

Chords and tendency tones

When a scale is then used to construct chords, these tendency tones are inherited within the chord. Each unstable tone present in the chord still has its tendency to resolve as in the pure melody case. In turn, this means we can group together chords by whether they have one or less unstable tones, or two unstable tones, or three unstable tones present. Based on this, I, III and VI triads from major scale contain none or one unstable tone, so are considered stable chords, creating no desire in the listener for the chord to move elsewhere. Next, II and IV both contain two unstable tones and can be thought of as "medium-drive" chords. Finally, V and VII contain three unstable tones, so can be considered as "high-drive" chords. Together, the medium-drive and high-drive chords are the unstable chords built from that scale.

So, we can then think of chord progressions as wandering between stable, medium-drive and high-drive chords. Moving from lower drive to higher drive creates expectations that a lesser drive chord needs to follow. Doing the opposite ramps up expectations further.

Scale and chord progression

For starters, you can play the stable scale tones over any chord built from that scale, but watch out for emphasising the <1> tone of the scale over the <V> chord from that scale - you may want to use the neighbouring <7> tone of the scale instead (or b7 if the scale contains a b7). The reason for this is that the <1> will grate against the middle note of the V triad, if that triad is a major triad. Its middle note is the <7> of the scale, and chords don't appreciate notes a semitone above a chord note - it sounds very jarring.

So, bearing that warning in mind about V and <1>, you can play the stable tones across an entire chord progression based on chords from that scale. For more interest add in the tendency tones, resolving them as expected if you like (same warning applies though - don't resolve from <7> to <1> over a V, unless you want to create this clashy sound). In essence, we're just thinking about the melody in its own right and pretty much ignoring the chords.

What's left then is using non-stable chords and non-stable scale tones together. If you think about it, if you want to enhance the tendencies within an unstable chord, to build the expectations of the listenere, it makes sense to play unstable tones from the scale over the top, and especially the two most unstable scale tones, and resolve these when the chord moves.

A mode and chord progressions built from that mode

Now the above applies just as much where the scale is a mode, and the chords are built from that mode. For example, Mixolydian (1, 2, 3, 4, 5, 6, b7) has the following triads: I maj, II min, III o, IV maj, V min, VI min, and bVII maj. Its seventh chords are: I7, II-7, III-7b5, IV maj7, V-7, VI-7, bVII maj7.

With Mixolydian, the unstable tone rankings from least unstable to most unstable are <6>, <2>, <b7>, <4>. The two most unstable tones in this mode are thus <b7> and <4>, with <4> having the strongest tendency. Resolutions are: <6> to <5>; <2> to <1>, <b7> to <1> and <4> to <3>.

As before, we can then assign chords as stable, medium drive, and high-drive based on the number of unstable tones present. The assignment depends both on the number of unstable tones, but also the strength of their instability. Looking at these chords, we get the stable chords are I, III and VI. Medium-drive chords are IV and V, and high drive chords are II and bVII.

To give you guys a bit more choice, here is the set of chords, including seventh chords, categorised by drive, with the most unstable at the top and the most stable at the bottom. Any chord can be chosen as representative of its group.

Here are a few chord progressions to try:

I7 repeat
I7 III-7b5 repeat
Imaj I7 IVmaj bVIImaj7 repeat
Imaj bVIImaj7 VI-7 bVIImaj7 repeat
Imaj bVIImaj7 VI-7 V- repeat
bVIImaj7 I7
bVIImaj/I I7 (i.e. play bVIImaj over a bass note I (the key note) ... the I plays throughout)

What happens when the chords don't all come from a particular scale

This is where the modes shine. One possible chord progression for a mode is simply repeating the I chord. So, everything we've mentioned above holds. As it happens, there are certain chord types that simply have a nice sound, and there are many tunes where a chord is used for its sound, and then the root of the chord changes. For example, A7 is played for a while, followed by C7, then G7 and this all repeats. We're definitely not in A Mixolydian throughout - for starters, we need C# rather than C, and if we had C#, it would have to be C#m7b5 to belong to A Mixolydian). There are two very popular modes used to play over a dominant 7 chord: Mixolydian and Lydian b7 (Mixolydian with <#4> instead of <4>). So here, we just change to the appropriate start note of the mode to match the chord. Hence, we could play A Mixolydian, C Mixolydian, G Mixolydian.

The same can be done with the blues, as each chord lasts several bars - so a 12-bar blues in A, using the chords A7, D7 and E7 could use A Mixolydian, D Mixolydian and E Mixolydian. This can help add some ear candy along with the A minor blues scale across the entire progression, for example.

And when playing over one chord, to generate tension you can try emphasising more unstable notes in your solo or melody, and then return back to the stable notes. From the table above, bVII maj7 is the most unstable chord, so you could use this (arpeggiated) for this purpose. For example, over A7, play a melody involving the notes from Gmaj7, and intertwine with notes from A7.

Final comment

All the above is very much influenced by the genre of music. In Rock, Metal and so on, Mixolydian gets used a lot, and no-one gives a damn about resolving the <4> to <3> against the I chord. Those genres like the roughness created.

Finally, resolutions are simply expectations, and these are made to be broken!

Music theory is not about hard-set rules that must be obeyed. It's only summarising commonly used approaches, and everyone looks for ways of abusing these approaches, but musically (hopefully!)

In another article I'll talk about the modes whose jobs are to create a lot of instability to create even higher expectations of a stable chord following. I hope this article has been interesting.