Another ways modes are used is modal music. Like when you are asked to play over one chord or a one note
backing for a while. This would be similar to music that contains "drones" or "one chord vamps".
This is where the true light of a mode shines.
Lets say you are ask to play over a Dm7 chord for a whole tune, you're just asked to "improvise over that
What do you play?
Well, you would play a scale, or a Mode that fits over a Dm7 chord, or one that actually BUILDS a Dm7
There's a couple of ways to figure this out:
1. One way is, you could find all the Major keys that contain a Dm7 chord, and experiment with those keys. The Key's of C, Bb, and F come to mind as they each have a Dm7 chord within their Key. This can be time consuming but is a great practice technique to burn these concepts into the old noggin.
2. Another way is, you can look at ALL the Modes that BUILD a m7 chord. Remember these could be Dorian, Phrygian, Aeolian, Locrian, right? Then you can experiment with each of those starting with D as your Root. So, you'd try D Dorian, D Phrygian, D Aeolian, or D Locrian.
3. Or, I guess you could even interchange those Modes ideas in #2 if you wanted. Since it's a one chord
vamp, there is no other chord is involved to dictate the key you're in, or which one of those Minor
sounding modes to use. So, play one one those Minor Modes from D, then change to another, then another one. Experiment!
This is also true for playing over a straight Major chord for a long time. Say you need to play over a G Major chord vamp. You could find all the keys that contain a G Major chord (the Keys of G, D, C come to mind), or you could experiment with each of the modes with G as their Root that BUILDS a G Major chord (G Ionian, G Lydian, G Mixolydian).
Experiment with those three until something "clicks".
This experimentation would also hold true for a Gmaj7 vamp. You'd find all the Keys that contain a Gmaj7
chord. The Keys of G and D come to mind as the Gmaj7 could be the Imaj7 chord of G, or the IVmaj7 chord of the Key of D.
By knowing about the chords, you can jump right in with some scale ideas, some basic things to try.
So, please experiment with these concepts as that knowledge is some of the most common tools people use for improvising.
Let's say ALL you are given to play over is a straight E Note droning with a rhythm background. This is nothing but and E note, not an E Major chord, and an E Minor chord, just an E Note.
What do you play?
Well the first thing you would find out is whether that note is Major or Minor...Hmmm...
It's one note, you don't have ANY harmony to go by telling whether to even think Major or Minor. And like in the last example, you don't have any other chords involved to dictate what key you might be in.
What the heck would you do here???
All you know is it's got to be "some sort of E Scale/Mode".
Since we are talking Modes here...
You can experiment with ALL Modes until you "stumble or fall" on something that starts to work for you. Once you find THAT, you have discovered the true meaning of Modal Music. You will KNOW when you got something that works, the mode, the intervals, will jump right out at you.
Try it. Record yourself a track with a beat and a droning E note, then go to town play each mode with E as the Root and discover the Mode/Modes. It a great exercise.
When you find the Mode, the notes, the Intervals, etc...the Mode will 'speak' on it's own. You'll hear it,
and it will be something that others hear too. It will be a direction, given the one note backing and sense
This IS what a mode is...it's in the right mode, the right frame of thinking, it sound right, etc...
This is why I say the names of the modes mean nothing, because when you hit the "right mode" you are going to know it, you'll be able to play endlessly it will just keep on working...regardless of the name.
Here's an example of me using an E Lydian scale/mode against an E drone. You can HEAR this mode speak. It
creates the atmosphere all on it's own and it could go for hours.
And actually, if you remember...the Lydian Mode creates a Major chord, a maj7 chord actually. But, in this
clip you'll HEAR that it's used in a very "Minor sounding" way.