5. Intervals

At grade three, we learnt how to identify intervals and to describe them with their full names - a type and a number, for example "perfect fifth".

We learnt that the intervals built from the tonic of a major scale are:

1- perfect unison

2- major 2nd

3- major 3rd

4- perfect 4th

5- perfect 5th

6- major 6th

7- major 7th

8- perfect 8ve (octave)

We also learnt that the intervals built from the tonic of a minor (harmonic) scale are:

1- perfect unison

2- major 2nd

3- minor 3rd

4- perfect 4th

5- perfect 5th

6- minor 6th

7- major 7th

8- perfect 8ve 

At grade 3, all the intervals we had to identify had the tonic as the lowest note.

At grade 4, we have to identify and write intervals between any two notes in any of the keys for this grade (up to 5 flats/sharps). In other words, the lowest note might NOT be the tonic of the key.

We will also learn two new terms - AUGMENTED and DIMINISHED.

Harmonic and Melodic Intervals

Intervals which are written with one note on top of another are called harmonic intervals.

Intervals which are written with one note after another are called melodic intervals.

These terms have nothing to do with minor scales!

Seconds

We'll begin by looking at the scale of G major:

We already know that the interval between the first two notes of the scale is a major second:

But what about the interval between the next two notes, A and B?

We know the interval is a 2nd, because we count two note names from A to B. But what type of 2nd is it?

To work this interval out, we need to FORGET for a moment that this is a G a major scale. Instead, we need to imagine that the lower of the 2 notes is the tonic. The lower of the 2 notes is A, so we imagine a scale of A major:

The interval A-B is part of the A major scale, so A-B is a major second too!

Let's try the next interval - B-C.

This time, we need to imagine a scale of B, because B is the lower note:

Here we can see that B-C is NOT part of the B major scale. So it's not a major 2nd. 

In the key of B (minor and major), the note C sharp makes a major 2nd with the tonic B. The interval we want to describe contains C natural.

This means the interval is smaller than a major 2nd:

When the interval is smaller, we change the type from major to minor. 

So, the interval B-C is a minor second.

(You might have noticed that a major second is the same as a tone, and a minor second is the same as a semitone. You can use this as a quick method to remember the difference while you're doing grade 4.)

So a minor second is smaller than a major second. What is bigger than a major second? An augmented second. ("Augmented" means "made bigger").

Look at this scale of B harmonic minor and look at the marked interval between G and A#.

Using the method above, first we count the letter names to check the interval number G-A = 2, so it's definitely a 2nd.

Starting on the lower note, we imagine a scale of G and start looking for A# - but there is no A# in G major (or minor).

We know that G-A is a major 2nd, and we can see by looking at the piano keyboard (above) that the interval G to A# is bigger than G-A.

This interval is bigger than a major second - it's an augmented second.

In fact, all minor harmonic scales contain an augmented second between the 6th and 7th degrees of the scale!

Thirds

All the thirds you'll find at this grade are either major or minor. Remember that major thirds are found in major keys, and minor thirds are found in minor keys - simple! Don't forget that a minor third is a smaller interval than a major third.

Here's an example from our G major scale - the minor third B-D is found in the scale of B minor. (B-D# is a major third). The major third C-E is found in the C major scale (C-Eb is a minor third). Remember to start by checking out the scale formed by the lower note of the pair!

Fourths

In grade 3 we learnt that all fourths are perfect. We don't use the words "major" or "minor" with 4ths.

In grade 4 we now discover that some fourths are bigger or smaller than the normal "perfect" 4ths!

Look at the interval from C to F# in the G major scale. We know that in the C major scale, the perfect fourth is made with the notes C-F.

If you look at the piano keyboard, you'll see that C-F# is a bigger interval. Just like with the 2nds (see above), we use the word "augmented" to say that the interval is bigger.

So, the interval from C to F# is called an "augmented 4th".

All major and minor scales contain an augmented 4th between the 4th and 7th degrees of the scale!

Minor scales also contain another augmented 4th, between the 6th and 2nd degrees of the scale. Here we've written out 2 octaves of B minor, because this interval crosses into the 2nd octave:

Intervals which are smaller than normal are called "diminished". (Remember, we don't use the word "minor" with 4ths).

Minor scales contain a diminished 4th between the 7th and 3rd degrees of the scale:

The lowest note of the pair here is A#. We know that the interval A-D is a perfect 4th, and A#-D is smaller, so it's a diminished 4th. (Note - we didn't try to create the scale of A# major to test this. If the lower note has an awkward accidental you can check the scale of the natural note instead. A-D is easy to see as a perfect 4th, whereas the scale of A# contains the notes A#, B#, C##, D#, which is a bit awful!!)

Fifths

Just like fourths, fifths can be perfect, augmented (bigger) or diminished (smaller).

Here's an augmented 5th in B minor - between scale degrees 3 and 7:

Remember D-A is a perfect 5th, and D-A# is bigger, so it's an augmented 5th.

And here is a diminished 5th, also in B minor:

A-E is a perfect 5th and A#-E is a smaller interval.

Sixths

Like thirds, all the sixths you'll find in grade 4 are either major or minor. Here's a major and a minor 6th in G major:

A-F# is a major 6th, because it's part of the A major scale.

B-G is a minor 6th, because it's part of the B minor scale.

Sevenths

Sevenths can be major, minor or diminished at grade four.

Remember that 7ths built from the tonic are always major 7ths (even in minor scales).

7ths which are ONE semitone smaller than major 7ths are minor 7ths.

7ths which are TWO semitones smaller than major 7ths are diminished 7ths.

Here are some examples in B minor:

The interval from D-C# is a major 7th. (It's part of the D major scale).

The interval from E-D is a minor 7th. (It's one semitone smaller than the major 7th E-D#).

The interval from A#-G is a diminished 7th. (It's two semitones smaller than the major 7th A-G#).

Summary

1) To find the interval number, count the letter names of the notes. (G-A# is a 2nd, but G-Bb is a 3rd, even though A# and Bb are enharmonic equivalents.)

2) To find the interval type, use the lower note and pretend it's the tonic of a new scale.

3) All intervals based on the tonic in major scales are major (2nd, 3rd, 6th, 7th) or perfect (unison, 4th, 5th, 8ve).

4) All intervals based on the tonic in minor scales are major, (2nd, 7th) minor (3rd, 6th) or perfect (unison, 4th, 5th, 8ve).

5) Major intervals are 1 semitone bigger than minor intervals.

6) Major or perfect intervals which are increased by 1 semitone become augmented.

7) Minor or perfect intervals which are decreased by 1 semitone become diminished.

Checking your Intervals

You can use the following tables to check any intervals while you're practising:

Don't try to learn these tables by heart! Here's how to use them:

Name the following interval, which is in the key of G# minor:

1. Use the second table, because it's a MINOR key (G# minor).
2. The lower note is the 5th degree of the scale, so find number 5 on the left.
3. The higher note is the 7th degree of the scale, so find number 7 along the top.
4. The interval is named in the box where these points cross: it's a major third.