Modes are a mystery to many people. That shouldn't be the case and it doesn't take much information to make sense of them. We all know that if the key signature on sheet music has no sharps (#) or flats (b) that the key is either C major or A natural minor. What we may not think about is that this is because C major is the Ionian mode and A minor is the Aeolian mode. A more complete way of saying this might be, A natural minor uses the notes of the C major diatonic scale where the key center is shifted to start at the 6th scale degree.
| 1 | Mode | Scale Degree Chord Type(Ionian) |
1 I |
2 ii |
3 iii |
4 IV |
5 V |
6 VI |
7 viio |
|||||
| 2 | Lydian | 4th | F | G | A | Bo | C | D | E | |||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| 3 | Ionian | 1st | C | D | E | F | G | A | Bo | |||||
| 4 | Mixolydian | 5th | G | A | Bo | C | D | E | F | |||||
| 5 | Dorian | 2nd | D | E | F | G | A | Bo | C | |||||
| 6 | Aeolian | 6th | A | Bo | C | D | E | F | G | |||||
| 7 | Phrygian | 3rd | E | F | G | A | Bo | C | D | |||||
| 8 | Locrian | 7th | Bo | C | D | E | F | G | A | |||||
| 1/1 | 16/15 | 9/8 | 6/5 | 5/4 | 4/3 | 45/32 | 3/2 | 8/5 | 5/3 | 9/5 | 15/8 | |||
| 9 | Maj Pent | G | A | Bo | D | E | ||||||||
| 10 | Min Pent | E | G | A | Bo | D |
Although the Western chromatic scale has twelve notes, the diatonic scale has seven notes. In the case of the C scale that is shown on line 3 of the chart above that they are C, D, E, F, G, A, and B. If the piece of music is chromatic (has more notes than the seven diatonic notes) then these extra notes would be shown in the music as a accidental with a sharp (#) or flat (b) mark at their first occurrence in a measure.
Notice that line 4 is the Mixolydian mode of C and it still has the notes of the C scale but the key center is the fifth scale degree (G). If we want the key of G major, we would put a sharp (#) on the leger line associated with F to show that F is is F# throughout the piece.
On line 6 we have the Aeolian mode of C (natural minor) which is shifts the tone center to the sixth scale degree (A). It is normally called the key of A minor. The way that you know that it is A minor rather than C major is to look at where the song ends. With A minor it will end on an A, rather than a C. Could you do this with the other modes? Yes.
Mode are diatonic scales where the key center is shifted to some scale degree other than the one that you normally think of. The notes are the same, but shifting it to a new tonic note changes the quality of it's sound. Note that the chart above shows the modes in circle of fifths order.
Lines 2, 3, and 4 show the major modes of Lydian, Ionian, and Mixolydian. The tonic interval for all of them is major; four semitones from 1 to 3 and three semitones from 3 to 5. Each of these modes has the notes for the major pentatonic scale (line 9). The notes that distinguish Lydian from Ionian (4#) and Mixolydian from Ionian (b7) are not present in the major pentatonic scale.
Lines 5, 6, and 7 show the minor modes of Dorian, Aeolian, and Phrygian. The tonic interval for all of them is minor; three semitones from 1 to 3 and four semitones from 3 to 5. Each of these modes has the notes for the minor pentatonic scale (line 10). The notes that distinguish Dorian from Aeolian (6#) and Phrygian from Aeolian (b2) are not present in the minor pentatonic scale.
Line 8 shows the Locrian mode. It's tonic interval is a tritone; three semitones from 1 to 3 and three semitones from 3 to 5. It does not have all of the required notes for either the major or minor pentatonic scales.
For many musicians, if it isn't major or minor it's modal. If you throw a word like Mixolydian at them they will look at you like you're a space alien. They have years of experience and a good ear. They hear it, and they play it. If you play from tablature (TAB), it doesn't really matter to you what it is, or what it's called, you just play what the paper says. If you read standard music notation (SMN) it's much the same. A song in G Mixolydian of C might have no sharps or flats in the key signature, or it might have a sharp in the key signature telling you it's G, and then have a flat mark by all the F#s to make them F, as if they were accidentals. Either way, you'll play it just fine.
So, what does it matter what you call it? If you have practiced your major and minor scales and use those patterns to play, then you know which note to alter in the pattern. Major? Flat the 7 for Mixolydian or sharp the 4 for Lydian. Minor? Flat the 2 for Phrygian or sharp the 6 for Dorian. Knowing the actual scale that determines what the notes are (G Mixolydian of C uses the notes of the C scale for example) keeps you from playing something sour if you think about the names of notes while you play. If you are playing a diatonic instrument, it tells you how you must tune, or which key instrument you must select, and at what position you must play it in to achieve the desired result. It has a large effect on harmony.
Chords, or other forms of harmony that restrict themselves to the notes of the scale that is being played is diatonic harmony. Most musicians know that the I-IV-V chords of major music are major, and that the i-iv-v chords of minor music are minor. They also know that if the music is modal that "Those chords don't sound right." There s a reason for that.
If you look at the bottom half of line 1 and at line 3 you are looking at the chords for C (Ionian) major. The I and the large C indicate that it is a major chord. Using the notes of the major scale for the 1-3-5 interval result in a major chord. I won't go through the logic of building the diatonic chords, you can see it for yourself, but the result is C (I (major)), D (ii (minor), E (iii (minor), F (IV (major), G (V (major), A (vi (minor) Bo (viio (diminished)). Major has upper case Roman numerals and a normal sized font for the note. Minor has a lower case Roman numeral for the chord and a smaller case letter for the note. Diminished has a o. Since modes are a scale, shifted to a new key center, the chords associated with the mode also shift. The result is:
| Lydian | I | II | iii | ivo | V | vi | vii |
|---|---|---|---|---|---|---|---|
| Ionian | I | ii | iii | IV | V | vi | viio |
| Mixolydian | I | ii | iiio | IV | v | vi | VII |
| Dorian | i | ii | III | IV | v | vio | VII |
| Aeolian | i | iio | III | iv | v | VI | VII |
| Phrygian | i | II | III | iv | vo | VI | vii |
| Locrian | io | II | iii | iv | bV | VI | vii |
Keep in mind that to achieve the sound that they want, jazz or blues players routinely play chords that do not follow the guidelines for diatonic harmony. You don't have to play diatonic harmony, what sounds good is good. But changing modes does change what chords (by position) will sound like.
Pentatonic scales have five notes. The most popular pentatonic scales are anhemitonic (no semitones). We can create an anhemitonic pentatonic scale by dropping the semitones from the scale. There is a valid anhemitonic pentatonic associated with five of the seven modes. Dropping the semitones from Lydian and Ionian makes no sense because their major 7 interval would cause you to throw away the tonic note.
There are examples of music that use all five of the remaining pentatonic scales but the far and away most popular ones are major, formed by dropping the semitones from Mixolydian, and minor, formed by dropping the semitones from Phrygian. They are the ones shown on lines 9 and 10 of the first chart.
The beauty of pentatonic scales is that they sound good, and are popular for improvising since there are no notes that will sound bad. The down side is that they eliminate the notes that distinguish the modes from each other. Those notes are often marker notes that give a piece its character.
Suppose you want to play "Cluck Old Hen." It's a minor pentatonic tune (sometimes Dorian) that is supposed to sound modal. It is played in situations where there will be people playing rhythm chords. Which chords? It is normally played in A with A, E, G, and some versions C chords (1-(3)-5-7). But which chords? A minor pentatonic could be a subset of Aeolian mode (i-(III)-v-VII), Dorian mode (i-(III)-v-VII), or Phrygian mode (i-(III)-vo-vii). Which chords are right? Since it is an old-time/bluegrass tune we can eliminate Phrygian due to it's tritone vo. The 1-3-5-7 chords for Aeolian and Dorian are the same so the choice seems clear. Interestingly, the choice is often one that breaks the guidelines for diatonic harmony (i-III-V-VII) or an ambiguous 1-5-7 progression where only the root and 5th are played without the 3rd. The 1-5 interval, often called a modal chord or a power chord works because of its ambiguity. For someone playing a diatonic instrument, like a mountain dulcimer, the 1-5 interval is often the only right choice.
Modes themselves are actually quite simple; a diatonic scale with a shifted key center. There is a way to think about them that suits any orientation, once you understand the implications of looking at them that way. The confusion comes from the Tower of Babylon that we built for ourselves by simplifying modes to major/minor/modal.
For someone who plays a chromatic instrument, using a word like Mixolydian might just invoke the space alien effect. To them, "June Apple" in A is just that. The fact that the G is not sharp just a modal thing. Someone who plays from paper may just think that that flat 7 note is an accidental. They can still play it.
People who play diatonic instruments are the ones who are burdened by modes since changing keys implies a mode change that they must cope with. A harmonica player will have to know that it's best to play a D harp in second position to play June Apple in A. A mountain dulcimer player might opt for a DAd tuning with a capo in the 4th fret. After that it's all music.