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Modes, Scales and Keys
Modes in Music
What does “Mode” mean in music?
The term “mode” has two distinct meanings. It can refer to “church modes” which were used to classify Gregorian chant in the 11th century, and it can refer to the scale systems used in folk and pop music. While there are overlaps between the two, it is the latter which concerns us in this article.
Folk melodies began to interest “serious” composers at the beginning of the 20th century, possibly as a reaction against the increased erosion of rural culture caused by the Industrial Revolution. Ralph Vaughan Williams was an important figure at this time. He set about collecting folk melodies that had previously existed only in the memories of country people and had never before been written down in staff notation, and he then incorporated folk elements into his own compositions. A growing interest in non-diatonic scale systems has continued since then. This return to the style of ancient times is known as neo-classicism.
Modes have also been widely used in pop, rock and jazz music since the turn of the 20th century to the present day.
What are the Music Modes?
A mode is a 7-note scale built on a certain pattern of tones and semitones. The easiest way to work out the modes is to play a scale starting on each of the white notes in succession.
Starting on C, we make the Ionian scale:
This, of course, is identical to the scale of C major. The semitones are marked with a bracket.
Starting on each successive white note produces the following scales:
None of these other scales is identical to any major scale, although the Aeolian is like the descending melodic minor scale (also called “natural minor”).
Each scale has two semitones and five tones within it. The semitones occur in different positions in each scale.
Each mode can begin on any note, just like major and minor scales do. And just like with major and minor scales, it is the pattern of tones and semitones that defines the scale.
So, for example, the Dorian mode always contains a semitone between the 2nd-3rd and 6th-7th degrees of the scale. Starting on G, the Dorian mode looks like this:
Key Signatures and Modes
The modern key signature system is closely linked to major/minor keys. We all know for example, a key signature of Bb and Eb represents either Bb major or G minor. This key signature system, however, does not work so well for modal scales.
There are two inherent problems. One is that the modes cannot be differentiated by their notes alone (a quick glance at the previous paragraph should remind you that it is possible to write a scale in each of the seven modes without using any sharps or flats.)
Secondly, the sharps or flats in use do not always correspond to the tonic suggested by an existing key signature. For example, in the D Lydian scale, we find F#, C# and G#. These notes correspond to the key signature for A major, but A is not the first degree of the scale, it is D.
The most common solution to this problem is to use the key signature that corresponds to the keynote of the scale, either in the major or minor form, depending on which is more appropriate. Thus, for D Lydian, we would use the key signature for D major, and add G#s as accidentals. For D Dorian, use the key signature for D minor, with B natural accidentals.
Another method is to use the key signature belonging to the parent key. On the previous page, all the scales are written with a key signature for C major (i.e. no flats or sharps). The Dorian mode starts on the 2nd degree of the scale (D), the Phrygian on the third degree (E), and so on. If you transpose all the scales into a different key signature, the relationships stay the same. For example, if you use a key signature for A major, then the Ionian scale is like A major. The Dorian is built on the second degree of the scale, so runs from B-B, the Phrygian runs from C#-C#, and so on.
Using this method, D Lydian takes a key signature of 3 sharps (because the Lydian is the fourth mode, and D is the fourth note in the A major scale), and D Dorian has a key signature for C major (because the Dorian is the second mode, and D is the second note in C major).
The advantage of this method is that there are no extra accidentals needed, but on the down-side it is somewhat complicated to work out what key/mode the music is in!
Major and Minor Modes
Each mode has its own unique sound, brought about by the differing position of the semitones within the scale. The first five notes of each mode also affect the way the mode sounds. The first six modes all begin like either a major or minor diatonic scale.
The Ionian, Lydian and Mixolydian scales start in the same way as major scales, with a major third and a perfect 5th. They are “major modes”.
The Dorian, Phrygian and Aeolian scales start with a minor 3rd and a perfect 5th, so they are “minor modes”.
The Locrian is a diminished mode, because it contains a diminished 5th.
It can be helpful to notice how these correspond with the diatonic triads, i.e. in a major key, chords I, IV and V are major, ii, iii and vi are minor and vii° is diminished.
Composing in Modes: Establishing a Mode rather than a Major/Minor Key
For students new to composing in modes, the first question that arises is usually “How do I make it sound like it’s in the [x] mode instead of just major?”
If you look at the modes based on the parent key of C (scroll up), for example, the pool of available notes for each mode is exactly the same, namely, A, B, C, D, E, F and G. So, what it is about a melody that defines it as one particular mode and not another?
The answer lies in the notes which are emphasised in the piece and the notes that surround these emphasised notes, and the intervals between these notes.
In most melodies (modal or not) the focus of each phrase will be around the tonic and dominant of the scale. These are the notes we especially expect to see at the end of a phrase (in a cadence), but we will also see them being emphasised in other ways such as (and not limited to):
- Used more than other degrees of the scale
- Used on the strongest beats of the bar
- Repeated
- Accented
- Used in octave leaps
In all major/minor keys, the note before the tonic is a semitone lower. By contrast, in all modal scales (except the Ionian and Lydian), the step up to the tonic is a tone lower. Thus, it is important to make sure your melody moves from the 7th of the scale up by step to the tonic, ideally a number of times.
In all major/minor keys, the note after the tonic is a tone higher. In the Phrygian and Locrian modes however, it is a semitone. Thus, in these modes, you will need to ensure the melody moves from steps 1-2 of the scale several times.
Whichever mode you are in, you need compare it with a major scale for major modes, or the minor harmonic scale for minor modes. Where you see a difference, you need to make sure that this interval is used in your composition. This will prevent your melody from sounding major/minor.
Here are some examples.
The melody below was intended to be in G Aeolian (G-A-Bb-C-D-Eb-F-G). However, it sounds like it could also simply be in G minor (or G Ionian).
A quick glance at the position of semitones in the Aeolian scale compared to the G minor harmonic scale shows that the 7th-tonic interval is different. We would expect F# to lead to G in G minor, and F natural to G in G Aeolian. The absence of Fs of any type means we cannot define this melody as one or the other.
So, let’s rewrite the melody to ensure we include some movement between the 7th and tonic. I have added an F auxiliary note in bar 1, and altered the melody slightly in bar 3. (If these notes had been added in the context of G minor, they would need to be F sharps).
The melody now sounds modal. However, it could equally be Dorian or Aeolian mode! Again, let’s compare the two scales:
This time the difference shows up in the 6th-7th degrees of the scale. We will therefore need to use at least one Eb to ensure the Aeolian scale is defined.
The melody now contains all seven notes of the scale. This is one way to ensure that the correct mode is defined. However, it is not the only way. Consider the following facts:
- All the modes of one parent key contain the same tonic note (e.g. C as the key note).
- All modes contain the same dominant except the Locrian (which as a diminished 5th instead of perfect).
- All major modes contain a major third above the tonic, and all minor modes a minor third.
- The difference between the three minor modes is in their 2nd and 6th degrees of the scale.
- The difference between the three major modes is in their 4th and 7th degrees of the scale.
We can then draw the following conclusions when considering essential notes of the scale:
- Always use the tonic and 5th, as they are harmonically essential
- Always use the 7th, as this is the biggest non-major/minor marker
- Always use the 3rd, as this defines whether the mode is major or minor
- In major modes always use the 4th
- In minor modes, always use the 2nd and 6th
Some Examples of Modal Compositions
Dorian: Another Brick in the Wall (Part 2) (Pink Floyd), Scarborough Fair (anon.)
Phrygian: Jaws (movie track by John Williams), Hungarian Rhapsody No.2 (Franz Liszt), Fantasia of a Theme of Thomas Tallis (Vaughan Williams)
Lydian: E.T. (movie track by John Williams), The Simpsons Theme Tune (Danny Elfman), Mazurka No.15 (Frédéric Chopin)
Mixolydian: Sweet Home Alabama (Lynnard Skynnard), The Sunken Cathedral (Claude Debussy)
Aeolian: Losing my Religion (R.E.M.), Someone Like You (Adele)
Locrian: Night and Day (Cole Porter), Les Troyens (Act 2, scene 2) (Hector Berlioz)