Episode 9: Understanding Intervals Part 2

(pic from icawa)
Hello and welcome back everyone! Now as I left off with this series, we talked about the basic intervals; Major Minor and Diminished. Now I'm going to add two more intervals to the set that you know and a a couple of special cases you may have heard of. As always, if this interests you then don't be afraid to add to the friend pages on Twitter and Facebook!

Now to review what we talked about last week, we went over the intervals and how to tell them apart from one to the other. As I showed with the chart at the bottom of the post, it is nothing more than following the half steps between the notes. So in case it was a little confusing that way, here is another way of thinking about it.

Original Chart:


       Minor         Major        Perfect
1                                                    0
2        1                 2
3        3                 4
4                                                    5
5                                                    7
6        8                 9
7        10              11
8                            12

Simpler Chart:

       Minor         Major        Perfect
1                                                    0
2        H                 W
3     W+H             2W
4                                                  2W+H
5                                                  3W+H
6       4W             4W+H
7       5W             5W+H
8                            6W

H= Half Step

W= Whole step (2 Half Steps)

Now the new material I wanted to mention to you is a Diminished (o) interval and Augmented (+) interval. A diminished interval is an a half step below a minor interval and an augmented in a half step above a major interval. So for example we have a G-Bb which is a Minor 3rd (G-Ab-A-Bb), then a step below that is a G-Bbb (B double flat). Another example would be an D-Fb because a D-F is a minor 3rd, but lowering it down a half step makes it a diminished interval. Another way to look at the same interval is a D#-F. D-F in a minor 3rd, but raising the base note still closes the gap in between the notes. Now looking at augmented intervals, let's take a G-B which is a major 3rd. If you add a half step to the B you have a G-B# which makes it an augmented interval. Another way to see it is a Gb-B would be an augmented 3rd. Don't let the enharmonic spelling throw your answers off. A B# might sound like a C, and is an enharmonic spelling of C, if the note they write is a B then the notes around it must fit the occasion. Another example of augmented intervals is a G-C#. G-C is a perfect 4th, however with the addition of the sharp we have an Augmented 4th and the first of our special conditions.

The example mentioned above (G-C#) is an augmented 4th, but it is also a tritone. A Tritone is the a series of notes that are the exact middle of our 12 tone interval system. G-C# is 6 half steps from either tonic and give a very dissonant and very identifiable sound to music. A tritone consists of either an augmented 4th or a diminished 5th. Both are in the middle of our scale system.

Another way that I think makes learning intervals easier is the use of inversions. An Inversion is the process of moving one note an octave higher or lower to find an interval. The rule of inversions is if an interval is major before the inversion then the inverted interval is minor. The reverse is true as well, if an interval is minor then inverting it will result in a major interval. So a M6 would invert to a m3 and a m7 would invert to a M2. Perfect intervals always invert to perfect (P4 inverts to a P5, and PU inverts to a P8). Then Augmented always inverts to Diminished. That's why there are two notes that make up the tritone, augmented 4th and diminished 5th.