Mode, or Modal Scale: a seven note scale based on the major scale (aka the Ionian mode), in which one or more notes have been altered by one semitone in either direction. The natural minor scale is technically a mode of the major scale (Aeolian), but is considered to be just as musically useful as the major scale. Modes that have many notes in common with the minor scale are often described in relation to the minor scale. This means you could describe the Phrygian mode as either a major scale with a flatted second, third, sixth and seventh, or as a minor scale with a flatted second.
There is a huge misconception here on UG: That the method of deriving major scale modes by starting the scale on a different degree will yield scales with different root notes and scale patterns that will "magically" work over the original key, and allow the player to use seven entirely different scales over the same music. This is usually put forth by people who have read about music theory regarding modes, but don't test its practical application in real-world music situations.
The fact that modes can be derived by re-ordering the notes of any major scale is pretty cool, but it's just a mathematical coincidence brought on by the fact that the notes repeat to infinity. You can technically derive modes from any scale, since it's just a pattern chosen from repeating notes. You could theoretically find the modes of a modal scale, if you wanted to. Modes are simply new scales derived by changing the tonic (root note) in any given scale. The standard modes are the ones derived from the Major Scale.
If you derive C# Aeolian from the E major scale, it does not mean that C# Aeolian can be played over E major progressions. It means that you've built a C# minor scale, and are now playing in C# minor. I cannot stress enough that modal scales are their own separate scales, and are not tied to the key of the scale they were derived from, and are certainly not in the same key as the scale they were derived from.
In reality, true modal music is rare, hard to write, and doesn't offer much flexibility to the composer before they have to step outside the boundaries of modal music, or risk introducing really harsh dissonance and tension to parts of their music. Modal music requires that, without exception, all notes played in a piece are taken from a modal scale, and nowhere else. This includes notes played in the chords under the melody, all passing tones, lead-ins, etc
Let's go into some detail
What we always see in the Musician Talk section of UG is the following:
Q: I have chords in E major. What scales/modes can I use over these chords?
A: Well, you could use E major, F# Dorian, G# Phrygian, A Lydian, B Mixolydian, C# Aeolian, or D# Locrian.
This is incorrect. These scales all contain the exact same notes. Played on their own, they are real scales in their own key, but what people are always asking is what scales to play overtop of other music. This is where context becomes important, and this is where modes lose a lot of their perceived functionality.
No matter what way you slice it, if the band is playing in E major, you playing the notes E F# G# A B C# D# overtop of it will always, always, always be heard as an E major scale. Re-ordering the notes into a modal scale will simply sound like you've re-ordered the E major scale, and are still playing it, but now you're notes don't resolve anywhere, and sound unrelated to the what rest of the band is playing.
What some people in the forum try to put forward, and what I have argued for in the past myself, is that you could, in a roundabout way, use a fingering pattern based on the intervals of a derived modal scale (ie: C# minor played over E major). The notes are the same, after all. But a scale is only given a name based on the order in which you play the notes, and the key you are playing in is determined by what the whole band is playing as their root. Logically, there should be no need to think of a different scale other than the one you are in, regardless of what pattern you are playing.
So let's see a few examples. We'll have a theoretical band playing a progression in E major. The common misconception is that you can pick any mode derived from the original key (ie: C# Aeolian is the relative minor of E major, aka the sixth mode of E major) and play that mode over the original progression. But if you are playing notes of the E major scale, starting from C# and finishing on C#, it will just sound like totally improper use of the E major scale, because the band is obviously playing the key of E major.
It is certainly possible to choose fingering patterns that are based on what you would play for a modal scale, but the notes that will sound strongest to the listeners are still the ones the band is emphasizing (ie: the root, fourth and fifth chords of E major). If you are constantly trying to tie everything to a C# note instead, the audience will hear a solo that only sounds like it fits for a few notes at a time, and it will lack resolution, as the band keeps resolving to something in E major, and you keep focusing on C# and playing minor intervals from the C#.
This raises another problem - if the band is playing minor intervals between some scale degrees, and you are playing major ones, even if some of the notes harmonize some of the time, it's going to sound like someone is lost, or has forgotten their part completely.
If you are attempting to play a minor scale over a major key, you will end up with a situation like this: The band is going from, let's say, the fifth to the sixth degree of the scale within a bar of music. In E major, that would be going from a B chord to a C#m chord. If you are playing in C# minor for the solo, and you want to follow with the band, your fifth in C# would be G#, and with your minor scale pattern, you'd be going to the A as your sixth.
So the band plays their V chord, and you play your fifth note of C#, (a G#, which sounds to the band like a major third). Then you've got the band moving by a whole step to their vi chord, and you're moving by half a step (which in itself often makes it seem like someone screwed up), and then landing on a note (A) that the band regards as their perfect 4th, but you regard as your minor sixth. Even in the rare instance that a cool harmony shows up in these situations, you still end up with a group of musicians doing different moves in different keys, and chaos will ensue pretty quickly.
The best use of modes is to add accidentals to spice up the key you're already in. For example, adding a #4 to a major scale melody played over major chords in the same key (ie: an A major scale with a Lydian-esque #4, played over an A major progression), will add what people commonly refer to as a "modal" sound to the melody. But the reality is that it's more of a "major-scale-with-an-added-note" sound than it is a "Lydian" sound or a "modal" sound.
A few other notes on this topic use the altered notes as lead-ins, passing notes, or some other kind of flourish, but not as your main notes. Playing Dorian doesn't mean that you focus on the major 6th more than the other notes... it just means that within your minor scale, when it comes time to play the sixth, you're making it major instead of the usual minor.
Modes In (And As) Chord Progressions
Another thing I'd like to address is the following... people often ask "is there a way to create complex chord progressions that work flawlessly with a lead part played in a modal scale?" The answer is not really. You would need to alter one of the main notes in three of your triads (and four of your chords if you're using sevenths) just to use a mode with one altered note. It's one thing to alter a seventh, or even a third, but having to change the root note or the fifth of a chord can really mess things up. In short, trying to include the mode itself in the chords is a fool's errand most of the time.
A simple example would be the Phrygian mode... it has a flat (or minor) second. If you try to play the V chord in the (hypothetical) key of E minor Phrygian, it will sound like you made a mistake, because the root note is too dissonant with its own fifth (which is now F, not F#), since that fifth had to be altered to fit the Phrygian formula. It would also cause your diminished second chord to become a major chord instead, and your VII chord, normally major, would become minor.
What about Lydian? That #4 might sound good in the solo, but if you build it into a chord progression, it creates a IV chord that clashes with the I and the V chords, and which clashes with its own fifth. This will force you to avoid the IV chord most of the time. Also, the ii chord would become a II (major) chord in a Lydian progression and the diminished chord on the seventh degree would become a minor chord.
Now, it appears that some of these newly created chords are pretty standard; just majors instead of minors most of the time. But the chords cease to function properly within the key when we alter them with modes. You always end up with at least one diminished chord that sounds way out of place, and the newly formed chords which appear standard will still sound a little out of place, like they don't reinforce the chord that preceded them, and they don't properly imply the chord that will follow. I guess you could say they'll sound half wrong.
Well Then What The Hell Good Are These Modes, Anyways?
So how do you actually use modes? It seems like I've just spent several pages explaining their limited application... what you do to use modes is to not even think about them at first. Don't set out to write a modal solo. When the band plays a chord progression, just play along in the right scale. As you play, listen to the notes you are playing and how they interact with the band's notes. If the band plays in a major key, I would recommend trying to throw in an accidental based off one of the more "major-sounding" modes, such as Lydian (major scale w/ #4) or Mixolydian (major scale w/ b7).
There is no universal, fail-safe "use-the-note-here-and-not-there" rule. The best way to test out the usefulness of a modal note in any musical situation is to just substitute it in. First, play a melody using the normal major or minor scales. To try something modal, simply replace one of your notes you just played with its modal alteration. If you played a major scale, turn the 4th into a #4 and see how that sounds.
Don't overuse the modal notes either sometimes the modal note will only work one time in one place in the whole progression. Remember to think of it bar-by-bar... just because the #4 works in one bar doesn't mean that the regular 4th won't work in the next one. Or you could even do a 4th-to-#4 hammer/pull-off lick. Long story short: Experiment!
A few other quick notes... the Locrian (minor scale w/ b2 and b5) mode is by far the least applicable mode in most music. Due to its diminished fifth, it is considered too dissonant to use in most situations. The modes that work best when applied to minor keys are Phrygian (minor scale w/ b2) and Dorian (minor scale w/ #6). For major keys, start with Lydian and Mixolydian.
To conclude, the best use of modes is to add accidentals that can be theorized as "modal notes" to your standard major and minor scales. I will emphasize again that modes are not a magical musical tool to allow you to play out of key and still sound perfect, and that reordering the same scale notes over a constant progression will still yield the same scale. It's only called a mode and/or modal music if you're in the key of that mode already, and are using only the notes from that mode.
So what I recommend for you budding theory experts is to learn about intervals, and then learn the interval patterns of the modal scales. This will help you to understand how and where to add these mysterious "modal notes" to create rich harmonies and sounds. And above all, remember that if something sounds good, it IS good.
By Tom LeBlanc (aka FrigginJerk)