Understanding Intervals - Part 3



OK, but what about the augmented 4th and the diminished 5th? How do I know which one of those to use. Let’s look at some examples:

Firstly the Lydian scale:

0        3
o-||---|-x-|---|-x-|---|-x-|-x-|---|-x-|---|-x-|-x-|

(This one is used in the Simpson’s theme tune)

What do we call the note at the sixth fret?
For this we apply the same rationale as before. Because there’s already a perfect 5th in there we can’t call it a dimished 5th. But there is no perfect or dimished 4th so we can called it an augmented 4th.

Second example:

The Locrian scale (possibly the darkest sounding mode of the Major scale):

o-||--x-|---|-x-|---|-x-|-x-|---|-x-|---|-x-|---|-x-|

Again, what do we call the note at the sixth fret? Its just as simple as the previous example. Here we do have a perfect 4th but we don’t have a perfect 5th so we call the note at the 6th fret a dimished 5th. Easy.

Now, lets take an even more unusual example:

This is a scale you might find in country music or blues:

0-||---|-x-|-x-|-x-|---|---|-x-|-x-|-x-|---|---|-x-|

This one has the root, a major 2nd, minor 3rd, dimished 4th, perfect fifth, minor 6th and dimished 7th.

Obviously when you start looking at scales with more than 7 notes - e.g. the Diminished scale or even the Chromatic scale - you’re going to have to start doubling up. But still it’s a system that works well in most situations.

Understanding Musical Intervals - part 4 >>