Theory Thursday: Gimme a Second

Intervals: The Second

Summing up what we've learned so far about intervals, we know that a) an interval is a relationship between two tones, b) raw intervals measure this relationship in terms of individual half-steps and whole-steps, and c) with harmonic intervals we measure the musical value of this relationship.

Today's lesson is going to focus on one of the smallest harmonic intervals: the second.

From last week, we learned that the interval between any tone in the A minor scale and its nearest neighbor is called a second. But if you play the A minor scale on your guitar (especially the A minor scale all on one string), the raw intervals between some of the tones is just a single fret -- a half-step, while the interval between the rest of the tones is two frets -- a whole-step. Remember our pattern of whole-steps (W) & half-steps (H)?

W H W W H W W

How can it be that the harmonic interval between every neighboring tone in the minor scale is a 2nd when we can see that the raw interval changes between whole and half-steps?

The answer is that both whole steps and half steps can be called seconds. But there's a catch…

When a second is made up of a half-step, it's called a minor second. Likewise, when a second is made up of a whole-step (two half-steps), it's called a major second.

NOTE: It is common to use M for major and m for minor. So if you see M2, it means major second, and m2 means minor second.

So with that in mind, let's have a look at the second intervals in the A minor scale:

A -> B : M2
B -> C : m2
C -> D : M2
D -> E : M2
E -> F : m2
F -> G : M2
G -> A : M2

The important thing for you to remember about the second interval is that it comes in a couple different varieties: major & minor. Remember that a minor second (m2) is ALWAYS a half step, and a major second (M2) is ALWAYS a whole step.

EXTRA: There is one more type of second, but we don't find it in our A minor scale, so we're going to skip it for now. It is called an augmented second, and it is made up of three half steps. We will get to augmented seconds later.

Review

• What is an interval?
• What is a raw interval?
• How is a raw interval different from a harmonic interval?
• What is the difference between a major second and a minor second?
• What are the common shorthand notations for major and minor seconds?