What Intervals Are

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Chapter 3 · Lesson 01

In short

An interval is the distance between two notes. We measure it by counting note names, from the first to the second, counting both ends. That gives us the intervals of a second, a third, a fourth and so on.

Lesson Notes

Until now we looked at notes and rhythm separately. Now we start looking at the distances between notes. The distance between two notes is called an interval, and it is the foundation for the scales and chords we will see later on.

01What an interval is

An interval is the distance between two notes. The farther one note is from the other, the larger the interval.

The two notes of an interval can sound one after the other, in which case the interval is called melodic, or at the same time, in which case it is called harmonic. A melodic interval is ascending when it goes up and descending when it goes down. The distance stays the same; only the way it is written changes.

The same interval, three ways to write it

Melodic ascending

Melodic descending

Harmonic

The same third (C-E) three ways. In the melodic interval the notes sound one after the other, in the harmonic one at the same time.

We name the size of an interval with a number: the second, the third, the fourth and so on. In this lesson we will learn how to find that number.

02How to measure an interval

To find the number, count the note names from the first note to the second. Count both ends, without skipping any note in between.

From C to E: a third

We count the note names, both ends included: C (1), D (2), E (3). Three notes, so the interval C-E is a third.

Notice that we count both ends. That is why from C to D, two neighbouring notes, the interval is a second and not a first.

03The intervals up to the octave

We measure every interval within an octave the same way. Starting from one note, here is what the distance to each next note is called.

The intervals from C

From C upward: unison, second, third, fourth, fifth, sixth, seventh, octave. Each time we count both ends.

When the two notes are the same, the interval is called a unison (or prime). When we reach the same name again one octave higher, it is called an octave (or eighth).

Intervals don't stop at the octave. There are larger ones too, the ninth, the tenth and so on, measured in exactly the same way.

04Same number, different size

The number alone doesn't tell us the whole story. Two thirds, for example, may not be exactly equal; one can be slightly larger than the other. Those fine differences, the quality of the interval, are what we will look at in the next lesson.

Recap

An interval is the distance between two notes.
We measure it by counting note names, both ends included, without skipping any.
From C to E we count C-D-E, so a third.
The intervals up to the octave: unison, second, third, fourth, fifth, sixth, seventh, octave.
The number gives the size. The quality is what we analyze in the next lesson.