Relative Keys

In this article, we will discuss what a relative key is and practice identifying minor and relative keys in performed and notated music.

What is a Relative Key?

Put simply, if we are given two keys, we can say they are relative if they share the same key signature. For example, the keys of D major and B minor both have two sharps in their key signature, but their tonics are D and B respectively. Thus, we can say that the relative minor key to D major is B minor, and the relative major key to B minor is D major.

So if we are asked to determine what a relative minor key to a given major key is, how can we do it?

Well, one approach is to count to the sixth scale degree of the major. For example, the relative minor of C major is A minor, which makes sense because:

C D E F G A B C

A is the 6th scale degree.

This pattern holds for every relative minor key. What about relative major keys?

Well, we can simply do this in reverse! 

A B C D E F G A

We can see that the third scale degree in A minor is C, which is indeed the relative major.

It is very common for a piece of music in a major key to modulate (change keys) to the relative minor, and also common the other way around.

Take a look at this example:

Listen to the excerpt of Magnetic Rag by Scott Joplin. Follow along in the score, particularly with the bass line in the bass clef. See how the note that feels like "home-base" changes from Bb to G at around the 1:00 mark? This is an example of a key change from a major key to the relative minor.

Now, take a look at the excerpt 1:25 to 2:00. What happens here?

Identifying Relative Key Changes in Music

So, how do we identify a key change like this in music?

Well, if it is notated/written music, we must look for a change in tonic. That is, a new section of music that uses a different note as "home-base." This will certainly be apparent in performed/heard music, but may be more trick in written music if the key signature stays the same. Let's revisit a piece we looked at in the previous article:

Does this excerpt change key?

Well, at first glance we don't see a change in key signature, so our initial instinct may be to say no. However, upon closer inspection, we see that even though the key signature doesn't change, the tonic note does. Usually (though certainly not always) an excerpt will start and end on the tonic. In this case, we start on G and end on B-flat. Additionally, we see that the note in the bass voice on the last beat of measure 15 is F, which is the dominant of Bb. Dominants want to resolve to tonics. Thus, we can conclude that the excerpt changes from G minor to Bb major, which both have the same key signature, thereby making it a relative key change.

Let's look at another example of a relative key change in performed music:

Listen to the excerpt at a piano if one is available. Hum the tonic, Eb, to yourself. Based on the sound of the scales that we've studied, do you think the excerpt starts in a major or minor key?

Now, listen to the part of the excerpt with the lyrics "...feel so bad." Which note does it end on? Is this new key major or minor? Hum this note out loud.

If your answers are different, then we have a key change. And, since the note you are humming is Gb, third of Eb minor, we know that the key change is a minor to relative major change. We will see how we can determine what the names of the notes were later, but for now, focus on the fact that the key changed from minor to major, and the tonics changed. This means that, in all likelihood, the key change was relative.

 Another activity to try is to hum the Eb, and then try to walk up the minor scale until you hit the tonic of the new key. If you indeed walked up to the third scale degree, then it is a relative key change!

Doing this activity is extremely useful, because this is how you'll be asked to do it on the multiple choice questions of the exam.

Try doing this activity on the same song, but for the excerpt that lasts from 1:45 to 2:16. What type of key change happens?

The excerpt's tonic is F until the very end. What is the tonic of the ending key?

Practice

Identify and notate the relative key/key signature for each of the following keys:

A major

A minor

C minor

Bb major

F# minor

Listen to the following audio excerpts and determine whether the melodies modulate to a relative key.

Answer:

Answer:

Answer:

Determine the keys for the following excerpts and describe the modulations as relative or not relative.