Theory Thursday: Intervals Part 1

Intervals, part 1

Leaping way back to our chromatic scale, it's time to explore another fundamental concept of music: the interval. An interval is the space between two musical tones. We're going to start with the smallest interval, but first, here's the chromatic scale again, but I shrank the tones with two names to make it more readable:

A A#/B♭ B C C#/D♭ D D#/E♭ E F F#/G♭ G G#/A♭ A

The space between any tone and its adjacent neighbor -- either above or below -- is the smallest musical interval -- there's nothing in between. This smallest interval is called either a semitone or half-step.

NOTE: I learned half-step before I learned semitone, so I'll use the term half-step, just out of my own comfort. Just be aware that half-step is the same as semitone.

So now you know that a half-step is the space between each of the tones in the chromatic scale. The half-step is also the interval from each fret on the fretboard to the next higher or lower fret.

For example, on any of the strings, if you start on the 5th fret, the 4th fret would be a half-step LOWER and the 6th fret would be a half-step HIGHER than the 5th fret. Make sense?

So as you may have guessed, if you skip over an adjacent tone, either higher or lower, the resulting interval is a whole-step. Half + half = whole, after all. Also, just as a half-step is also a semitone, a whole-step is also a whole-tone.

So using the same example of starting on the 5th fret, a whole-step higher would be the 7th fret, and a whole-step lower would be the 3rd fret. Got it?

Now let's look both the A minor scale and chromatic scale again. I've underlined and emboldened the tones that make up the A minor scale so you can see how it is a subset of the chromatic scale.

Chromatic: A A#/B♭ B C C#/D♭ D D#/E♭ E F F#/G♭ G G#/A♭ A

A Minor: A B C D E F G A

We've already seen that the interval between EVERY adjacent tone in the chromatic scale is a half-step, but that's not the case at all with the A minor scale. If you look at the bold & underlined tones from the A minor scale, you can see that the A minor scale starts on A, then whole-step to B, half-step to C, whole-step to D, whole-step to E, half-step to F, whole-step to G, then finally another whole-step back to A. Every time you skip over a tone, that's a whole-step.

If we use W for whole-step and H for half-step, the pattern for the A minor scale looks like:

W H W W H W W

Exercise A: Review of A minor scale

Take a look at the A minor scale exercise from a couple weeks ago (listed below), and look how that pattern of whole and half steps from above corresponds to the fret positions of the scale.

Exercise B: Shifting the Minor Scale around

What do you think might happen if you were to take the pattern of fret intervals that you use for the A minor scale, and start on a different fret? For review, here's the A minor scale from a couple weeks ago, in the three tone per string pattern:

What if you were to start on the 8th fret instead of the 5th fret, but play the same pattern, just 3 frets higher?

Without necessarily knowing what tones you were just playing, you just played a C minor scale!

Wait, what?!?

That's right! EVERY minor scale uses the same pattern of intervals:

W H W W H W W

Whichever tone you choose to start from becomes "1" (the tonal center) and the rest of the scale falls into place, solely based on the pattern of intervals.

That's pretty crazy, right?

Well, let's not get too ahead of ourselves. We're going to stay focused on the A minor scale, but I just wanted to give you a quick taste of how relatively easy it will be to apply what you know about the A minor scale to the other minor scales.

Review

• What is an interval?
• What are two common names for the smallest interval?
• What are two common names for the interval you would get if you were to combine two of the intervals from the previous question?
• What is the pattern of intervals for the A minor scale?