In music, the subject of modes is pretty intimidating. The idea is that since there are 7 notes in the scale, any one of them could be the first note of a different kind of scale. To make it worse, someone gave each of these scales a hard-to-remember Greek name. Apparently you're not a "real musician" unless you can remember and understand 7 different ways to play the scale.
I don't buy it. As a working steel guitarist, I've only ever used 4 of the seven modes in popular music. And they aren't all that hard to understand. Here they are:
Ionian (Major)
1 . 2 . 3 4 . 5 . 6 . 7 1
C . D . E F . G . A . B C
This is the scale from the Do Re Mi song. Most classic country and American folk music uses this scale. A lot of jazz, pop, swing and old standards use this scale. Reggae, too. As a steel guitarist, this is the main scale I am expected to know how to play. Most songs use the major chords 1, 4, and 5, and their relative minors 6m, 2m, and 3m.
Major scale songs also often use a 2 chord (D F# A notes in the example above), resolving to the 5 chord. Stepping out of a scale for one note of a chord is a common technique in all modes.
Mixolydian (Seventh or Dominant)
1 . 2 . 3 4 . 5 . 6 b7 . 1
G . A . B C . D . E F . G
The very first thing you need to know to play rock is that the 7th note is flatted. If you noodle around on this scale a lot, you can sound like Jerry Garcia of the Grateful Dead.
The most used chords in the dominant mode are 1, b7, 4, and 5. Notice that the 5 chord steps out of the scale a bit (D F# A in our G Mixolidian example above), in the same way that a 2 chord steps out in major mode.
The b7 chord plays a big role in mixolydian rock. Think of the Marshall Tucker song "Can't You See". The song is in D and the chords are D C G D (1 b7 4 1). A traditional country song with G, C and D would be in G major. It's the same chords, but the key and scale are clearly different.
Dorian (Minor)
1 . 2 b3 . 4 . 5 . 6 b7 . 1
D . E F . G . A . B C . D
When you flat the third note of the mixolydian scale, you get the most popular jamming scale for rock and blues. Dorian minor is the basis for the pentatonic (5 notes per octave) solos made popular by guitarists like Eric Clapton. Those pentatonic notes are 1, b3, 4, 5 and b7 (skip the 2 and 6 notes).
Dorian minor includes a major chord based on the b3 note of the scale. The main chords are 1m, b3, 4, 5, and b7. Notice that these are the same numbers as the notes of the penatonic scale!
As in dominant (mixolydian) mode, the 5 chord includes a note from outside the scale (A C# E in our D minor example above).
Many blues and rock songs use a dorian minor scale superimposed on a mixolydian chord progression. In other words, playing a minor scale over the major 1 chord. The soloist will play a penatonic minor scale, occasionally bending the b3 up to the natural 3 on the 1 chord to express an uplifting emotion.
Aeolean (Natural Minor)
1 . 2 b3 . 4 . 5 b6 . b7 . 1
A . B C . D . E F . G . A
The natural minor or relative minor scale is used in many minor key songs. The main chords are 1m, 4m, and 5m. Sometimes the 5 chord is a major (E G# B in our A minor example above). The b6 and b7 chords are also majors. In the 60's, many rock songs used the popular chord progression Am G F E, based on the natural minor scale.
The 5 note minor pentatonic scale is the same for both minor modes (Aeolean and Dorian).
Pop, modern folk and dramatic music often combine the natural minor and major modes to shift the mood from melancholy to hopeful or vice versa. A song will start in A minor (Aeolean), for example, and shift temporarily to C major (Ionian) for an uplifting section. Both modes use the same notes, but have different starting points. The 5 chord of the upcoming mode is often used to emphasize the transition. Example: (minor) Am Am Dm G7 to (major) C G F E7 back to (minor mode) Am.
Similarly, the natural minor mode is often used for sections of a major mode song. Since they share the same notes and their starting point is related (Am is the "relative minor" of C), the subtle transition isn't usually thought of as a "mode change" unless you analyze it closely.
In Conclusion
These are the 4 modes that a versatile musician should know. You probably already know one of these modes pretty well, maybe more. There are other modes that aren't used very often. Theory books tend to give all modes the same weight, but these 4 are the ones that are actually used on the bandstand.
Melody is an interaction between chords and scales. The mode tells you which scale to use to find the notes between the chord notes. That's why modes are important.
Some songs break the rules. Some musicians do, too. It's all good.
© 2013 by Bobby Lee