Welcome to my next article on basic theory. First, I must list a few corrections from the Oh When the Saints article so I can stay honest and avoid confusing you. I do apologize and will proofread better from now on for EVERYBODY'S sake.
1)The perfect fourth does not occur naturally in the Lydian mode as well.
2)Perfect intervals occur the same in MOST modes
3)In the paragraph before the So to recap, the sentence SHOULD read: "Secondly, they occur naturally THE SAME WAY in all of the modes except two. And with that, no mode has BOTH 4th AND 5th altered."
4)In the Intervals paragraph, the sentence should read, Since A is the 6th degree in the C major scale, we label it as a major 6th.
Since with the previously given information you should be able to build all of the modes, there will be no further need for explaining of those explicitly. But there are just a few remaining intervals and their qualities left as well as a brief explanation on the idea of what augmented and diminished intervals are.
Let's explore the three main intervals that are left in the major scale: maj2, maj6, maj7.
*The maj2 is one whole step from the root
*The maj6 is 4 1/2 steps from the root
*The maj7 is 5 1/2 steps from the root
Now, one important thing to remember is that these only describe the INTERVAL or the distance of that note from the root and NOT the quality of that mode derived from that note.
The other two intervals left are perfect unison and perfect octave. We won't worry much about these because they are simply either the same note, or the same note one octave (8 notes) up. And, since their function is usually that of the root of the scale, they are rarely altered.
Altering The Intervals:
There are a few basic rules as to how to alter the intervals according to their described quality (like major, minor). The ones for these are:
*When a major interval is lowered by a half step, it becomes minor.
*When a minor interval is raised by a half step, it becomes major.
That was easy. But now you may ask, What about the perfect intervals? This is where the idea of the augmented and diminished interval comes in. We already know that perfect intervals are NOT defined as major or minor by their very nature (how they sound). But, we do have the ability to alter them. We can INCREASE their distance or AUGMENT them. Or we can DECREASE their distance or DIMINISH them. So the rules for perfect intervals are this:
*When a perfect interval is raised by a half step, it becomes augmented.
*When a perfect interval is lowered by a half step, it becomes diminished.
That was easy as well! But there is a catch. Since the act of raising and lowering notes literally has scalar consequences, AND that the act of moving a note up or down ---regardless of quality--- can be expressed in terms of the ACT ITSELF, we can apply augmentation and diminishing to major and minor intervals as well. But as you will see, these rules are also symmetrical as well as logical. They are:
*When a major interval is raised by a half step, it becomes augmented.
*When a major interval is lowered by two half steps, it becomes diminished.
*When a minor interval is raised by two half steps, it becomes augmented.
*When a minor interval is lowered by a half step, it becomes diminished.
Notice how when a major is lowered by TWO half steps, it becomes diminished? There's a reason for this! If you only lower it by ONE half step, it becomes minor. So you must go 1/2 step beyond that in order to express that particular altering. Notice how the rule for augmenting minor intervals is EXACTLY the opposite? The same logic applies.
One quick thing to remember here, these intervals describe the distance of that particular scale degree in reference to the ROOT. So a unison is the interval of the note that IS the root. The maj2 is the distance that the second note is from the ROOT..... and so forth.
We already know that the major scale (ionian mode) contains all major intervals and both a perfect 4th and 5th. So we can say that it is constructed as such:
*unison, maj2, maj3, p4, p5, maj6, maj7, octave
Let's take the next major mode, lydian:
*unison, maj2, maj3, aug4, p5, maj6, maj7, octave
The next major mode, mixolydian (dominant)
*unison, maj2, maj3, p4, p5, maj6, min7, octave
Notice how all of the 3rds are major? Notice how there is only ONE difference between each mode? The lydian has an aug4, and the mixolydian has a min7.
Now let's do the minor modes:
*unison, maj2, min3, p4, p5, min6, min7, octave
*unison, maj2, min3, p4, p5, maj6, min7, octave
*unison, min2, min3, p4, p5, min6, min7, octave
Notice how, just like with all three major modes, there is only ONE note difference in each minor? The dorian has a maj6, and the phrygian has a min2. Remember, it is the third scale degree that makes a mode, scale, or chord minor or major. That is its quality.
What about the locrian mode? Actually, it isn't as scary as it sounds. Besides, the actual sound of it is great to use for metal. Let's analyze:
*unison, min2, min3, p4, d5, min6, min7, octave
Notice how firstly, it has all lowered intervals except the fourth. Also, notice that it has a diminished 5th! This ONLY occurs naturally in the locrian mode. You may ask what quality this mode is. It is diminished. Why isn't it just minor? Simple. It has BOTH a min3 AND and diminished 5.
So here are the two basic rules:
*when BOTH the 3rd is minor and the 5th is diminished, the chord, scale, or mode is considered diminished.
*If the 3rd is major and the 5th is raised, the chord, scale, or mode is considered augmented.
This is really all you need to know to be primed for how to build and understand chords and tonality. And that is exactly what I am going to talk about in my next article. We will explore creating triads (3 note chords) made diatonically (naturally) from noted within scales and modes.
Thanks for reading.
Reference for actual wording of Altering The Intervals rules.