Lesson 20: Key Transposition

In Lesson 18, we learned how to transpose music up or down one octave, sometimes into another clef. In this lesson, we will learn how to transpose music up or down into another key.

Take a look at the following short excerpt:

  

It is in G-major. We know this because there is one sharp in the key signature, and there are no D-sharps to indicate a leading tone to E-minor. (If this is not clear, re-read Lesson 16 (Key Identification)

Play the melody above several times. Now, try listening to this version:  

You will notice that although it starts on a different pitch, it somehow sounds "the same" as the previous melody. This melody has been transposed into a new key, F-major. Here is what it looks like:

  

There are several ways to transpose melodies, and it is recommended that you become familiar with all of them, and use one method to check against the other. The following three methods will assume that you have been given the original key, and the key that you will be transposing the melody to. Let's use these methods to transpose our melody from G-major to F-major.

The first step to using any of the following three methods is to place the clef, time signature, and the new key signature on a staff, like this:    

When transposing a melody into a new key, the scale degrees, or technical names, will remain the same. In other words, if the melody begins on the tonic in the original key, it will begin on the tonic of the new key. If it ends on the submediant in the original key, it will end on the submediant of the new key, and so on. In the first example above, the melody begins on the mediant (3rd degree) of the original key, G-major. Therefore, the new melody will begin on the mediant (3rd degree) of the new key, F-major:

You can then go through the entire G-major version of the excerpt, determine the technical name (scale degree) of each note, and write the same degree in the new F-major version.

Here is another way to do it:

METHOD 2. Transposing by Harmonic Interval

You know that the original key is G-major and the new key is F-major. Now determine the interval between those two notes:    From your knowledge of intervals, you know that the 'F' is a major 2nd lower than the 'G'. Therefore all the notes in the new melody will be a major second lower than the original G-major melody:

3. Transposing by Melodic Interval

Take the original melody and determine the intervals between each successive note of the melody:

Then determine the first note of your new, transposed melody. Do this by using Method 1 (Technical name). Once you have determined that 'A' is your starting note, apply the intervals of the original melody to the new melody, like this:

As stated before, it is advisable to use all three methods throughout the transposing process, checking one against the other. This is especially true when dealing with accidentals, or in situations where the melody is atonal. An atonal melody is a melody in which there is no tonal centre, and the music is not in any particular key. Study this rather complicated excerpt:

  

You might think that since the key signature has no sharps or flats, it is therefore in C-major or A-minor. But this melody has many accidentals that cannot be explained by either of those keys. Therefore we would be correct to say that the melody is probably atonal. If you listen to the excerpt, you will see that it does not seem to centre on any key. So how do we transpose it?

Obviously, if the key of the melody is irrelevant, we would not likely be asked to transpose it to a particular key: we would likely be asked to transpose it by a certain interval. Let's transpose it up a major 3rd. Our first note will be a major third above 'A', which is 'C-sharp':    We can proceed in this manner, transposing every note up a major third. Don't forget to check your progress using the other methods discussed in this lesson. For example, using Method 3 (melodic intervals) we know that the second note in this excerpt is a minor 3rd higher than the first note. Therefore, in our new transposed melody, the first note will be C#, and the second note will be 'E', and so on.

The third note in the excerpt is E-flat. We can transpose it correctly by either: Method 2 (harmonic interval)- writing the note that is a major 3rd higher ('G'); or Method 3 (melodic interval)- writing the note that is a major 6th lower than the previous note. Here is the melody, correctly transposed a major 3rd higher: