Musical Modes

There's always lots of confusion over how the various modes in music work. It's really quite simple, and I'll try to explain how I understand it here. Note that I play guitar and although the information is general musical theory, it is aimed primarily at guitarists.

There are seven modes, corresponding directly to the seven degrees in a major scale. In C major, the seven notes are C, D, E, F, G, A and B. Each of these notes can be used to construct a different scale. The first, Ionian is just the C major scale we started with. By taking the same notes, but starting from D instead of C and ending on C instead of B, we have constructed a new scale, D Dorian. We can start at any note and play the notes from the C major scale in order; each is a different mode:

All these scales contain the same notes, but they are different modes of different keys. They are all relative scales. Note that you may already be familiar with A Aeolian - it's the common A minor scale.

This method of deriving scales is particularly useful for improvising (on guitar at least). If, say, you decide you want to play in G Mixolydian, you just use the notes from C major (ionian) which you should know already, and change the degrees so that 1 is G, 2 is A etc up to 7 being F. Simple!

The above method derives relative scales in different keys, containing the same notes. What if you want to find all the scales in the same key ? There's another, harder but more general method for working out scales. Fortunately we can derive this new method from the simple method already known.

Look at the table above. The D Dorian scale consists of D, E, F, G, A, B and C. We know already that the D major scale is D, E, F#, G, A, B, C#. By comparing these scales, we can see that D Dorian is the same as D Ionian but with two notes flattened: the 3rd degree F# and 7th degree C# of the ionian scale become F and C in the dorian scale. This rule holds for all keys, and any dorian scale can be worked out by flattening the 3rd and 7th degrees of the ionian, or major scale.

Lost ? Here's a table to help:

The 3rd note and the 7th note are sharp in the major scale and natural in the dorian scale.

We can apply the same technique to any of the other five scales in the first table above. Want to know how to derive a Mixolydian scale ? G ionian is G, A, B, C, D, E and F#, but G Mixolydian is just G, A, B, C, D, E and F. Thus mixolydian is the same as ionian but with a flattened 7th.

By repeating the above process for all seven modes, any mode can be derived from the ionian (or major) scale by applying the following modifications:

Now, if you ask "What's E locrian ?" you can take E major (E, F#, G#, A, B, C#, D#) and flatten the 2nd, 3rd, 5th, 6th and 7th degrees to get the E locrian scale of E, F, G, A, Bb, C, D. "What's Ab Lydian ?" Ab Major is Ab, Bb, C, Db, Eb, F, G; we sharpen the 4th degree for lydian so Ab Lydian is Ab, Bb, C, D, Eb, F, G.

Right, you say - how do I use this new-found wealth of information ? In a given key, you can construct seven chords corresponding to each note in the scale from the note and two other notes - the 3rd and the 5th. These three notes are known as a triad. For example, in C major the chords are C major, D minor, E minor, F major, G major, A minor and Bdiminished. For each chord, there's also a mode

That's all there is to it. Next time you're jamming along to a chord progression you'll know exactly the scale to use for each chord. Well, perhaps you'll have to practice a little bit first.

I've just scratched the surface here, as these are just the seven major modes. There are also melodic minor modes, harmonic minor modes, and many other types of scale. The method for deriving each scale is identical, however. To derive harmonic minor scales repeat the above process starting with the A harmonic minor scale A, B, C, D, E, F, G#. From there, derive that B dorian harmonic minor is B, C, D, E, F, G#, A and repeat the whole process.

I hope this helps you understand the theory behind musical modes, and that you can now apply this information to work out just about any scale you like. I will appreciate any comments anyone has on this article - feel free to email me at the address below.

Happy playing!