Lesson 16: Key Identification

At this point, you probably feel quite comfortable with key signatures, and major and minor scales. The focus of this lesson is to be able to examine a musical excerpt and be able to tell what key it is in. We do this by looking at the key signature, if present, and/or accidentals throughout the excerpt.

Have you ever wondered what puts a certain piece of music in a certain key? We can take a look at this excerpt...

  

... and we can determine the key right away. First, we determine key by what accidentals are used, not necessarily by the first or final note of the excerpt. In this excerpt, the only accidental used is b-flat. Just as with our major scales that we did in Lesson 8, we can place a key signature at the beginning of this excerpt of one flat, the b-flat:

Note that in written music, the key signature appears before the time signature. An easy way to remember this is to remember that the letter 'k' ("key") comes before the letter 't' ("time signature"). You know from Lesson 12 that each key signature has two possibilities: a major key and a minor key*. For example, you will remember from that lesson that a key signature of one flat gives us F-major or D-minor. So how do we know which key this excerpt is in?

The note that most strongly defines the key we are in is the leading tone. The leading tone points to the tonic note. You learned this in the previous lesson when you learned why dominant chords must be major: so that there is a leading tone to the tonic. So in order for an excerpt to be in a certain key, there must exist a leading tone to the key. If this excerpt were in F-major, we would want to see the note 'E', particularly followed closely by an 'F', because that would indicate a leading tone followed by the tonic. Let's look at the excerpt and see if we have 'E' and 'F' in reasonably close proximity:

Yes, there are two instances in this excerpt where 'E' is followed by 'F'. But before we assume we are in F-major, we have to check out the possibility of this excerpt being in D-minor. The notes 'E' and 'F' also exist in D-minor, so just because we see them does not mean that we are certainly in F-major. We need to now check for the existence of a leading tone in D-minor. What is the leading tone in a D-minor scale? Answer: 'C#'. A quick check of the excerpt tells us that there are no C#'s. In order for this excerpt to be in D-minor, we need a C# leading tone somewhere. We don't have it - we have C-natural. So this excerpt is most certainly in F-major. In fact, it would make this process shorter to check the minor key possibility first, because we would have been able to determine right away that there was no leading tone to D-minor present.

Now that was a rather wordy paragraph, and I'd recommend that you reread it carefully before going on.

[NOTE: Why don't we say that the excerpt is possibly in D-minor, using the natural minor scale? The natural minor would not require the raised leading tone. The reason is that the natural minor scale is actually a mode, (the Aeolian Mode). It is indeed possible for an excerpt to be in the Aeolian Mode, but the melody would have to center on 'D', and definitely end on 'D'. I've written more on this point at the bottom of this page which I'd recommend you read. For now it is best to accept that even though we teach natural minor, the excerpts you see in this lesson will require the raised leading tone in order to be said to be in a minor key.]

Let's see what key this excerpt is in:

  

First step: make a list of the accidentals used: G# and F#. Can we put those in an order to make a key signature? Well, a key signature with two sharps would be F# and C#. So these two accidentals don't make a key signature right away. What if we consider that the F# is the key signature, and the G# is some other accidental. A key signature with one sharp would be either G-major (and the G# doesn't make any immediate sense) or E-minor (again the G# doesn't make any sense). So that doesn't seem to be a possibility. We have one more option to consider. Any time you see two accidentals one tone away from each other (F# and G#), it could be a melodic minor situation. In melodic minor, the 6th and 7th tones are raised. (The 6th and 7th tones are one tone away from each other.) If the F# and G# were the raised 6th and 7th tones, that would mean that the key we would be considering would be A-minor. You know that A-minor has no sharps or flats. If F# and G# have been raised from their normally natural state, that would mean that this excerpt is in a key that has no sharps or flats. We now know that this excerpt is in A-minor, because of the presence of the leading tone to A-minor (G#).

Here's another example:

  

In this excerpt we have been given a key signature of two sharps. So we know that it is either in D-major or B-minor. Let's check first for the presence of a leading tone in the minor- an A#. Yes we have one. But you may be surprised when I tell you that even though we have an A#, the key is probably D-major! Here is the reason why: The A# in this case is acting as a passing tone between A and B. It doesn't have a leading note function- it's simply ornamenting the line. And the proof is that in the next bar we see an A-natural. If the writer of this excerpt were to give us something other than an A-natural in the last bar, it would sound to our ears like B-minor. But the A-natural cancels out the leading tone to B-minor. The last bar emphasizes D-major through the use of the C# leading tone.

Here are some musical excerpts. The key for each one has been given. Look each one over, and be certain that you understand the reasons for each key designation:

1) A-major:    

2) C-minor:    

3) F-minor:    

4) E-major:    

5) B-flat major:    

* If your browser has a MIDI plugin, click on the play arrow to listen to a harmonization of these next three melodies. They are almost identical. The first one is in C-major, and the second melody is simply a transposition of the melody into the minor. Places where tonic chords would work are labeled with a "T", and places where dominant chords would work are labeled with a "D". You can hear how the raised leading tone in the second one (the b-naturals) cause the tonic chords to be strongly expected. The third excerpt is that same minor key melody, but without the raised leading tones. You can hear that the dominant chords lack the strong drive to move toward the tonic. In fact, this melody cannot be said to truly be in C-minor, as it is lacking the dominant chord. Without any leading tones we could say that the third melody is in E-flat major. However, later lessons will deal with modes, and you will learn that we have another way of classifying melodies that seem to center around a certain note ('C', for example,) but are not based on traditional tonic-dominant harmony. The third excerpt will actually be seen to be in either C-Aeolian or C-Dorian. But that's a topic for another lesson!

1) Key: C-major:
  

2) Key: C-minor (with raised leading tones):
  

3) No raised leading tones:
  

We have more to learn first before delving into the world of modal melodies. For now, let us assume that on the quiz for this lesson, melodies will either be major or minor.