6.4. Transposition: Changing Keys^*

In many ways, this is the most important step, and the least straightforward. The transposition you choose will depend on why you are transposing. If you already know what transposition you need, you can go to step two. If not, please look at the relevant sections below first:

If you have chosen the transposition because you want a particular key, then you should already know what key signature to use. (If you don't, see Key Signature.) If you have chosen the transposition because you wanted a particular interval (say, a whole step lower or a perfect fifth higher), then the key changes by the same interval. For example, if you want to transpose a piece in D major up one whole step, the key also moves up one whole step, to E major. Transposing a piece in B minor down a major third will move the key signature down a major third to G minor. For more information on and practice identifying intervals, see Interval. For further information on how moving music up or down changes the key signature, see The Circle of Fifths.

Figure 6.15. Find the New Key

You must know the interval between the old and new keys, and you must know the new key signature. This step is very important; if you use the wrong key signature, the transposition will not work.

Now rewrite the music, changing all the notes by the correct interval. You can do this for all the notes in the key signature simply by counting lines and spaces. As long as your key signature is correct, you do not have to worry about whether an interval is major, minor, or perfect.

Figure 6.16. Move all the Notes

Did you move the key down a minor third? Simply move all the notes down a third in the new key; count down three lines-or-spaces to find the new spot for each note. Did you move the key up a perfect fourth? Then move all the notes up four lines-and-spaces. Remember to count every line and every space, including the ones the notes start on and end on. Once you get the hang of it, this step is very straightforward, but it may take a while if you have a lot of music.

Most notes can simply be moved the correct number of lines and spaces. Whether the interval is minor, major, or perfect will take care of itself if the correct key signature has been chosen. But some care must be taken to correctly transpose accidentals. Put the note on the line or space where it would fall if it were not an accidental, and then either lower or raise it from your new key signature. For example, an accidental B natural in the key of E flat major has been raised a half step from the note in the key (which is B flat). In transposing down to the key of D major, you need to raise the A natural in the key up a half step, to A sharp. If this is confusing, keep in mind that the interval between the old and new (transposed) notes (B natural and A sharp) must be one half step, just as it is for the notes in the key.

Figure 6.17. Transposing Accidentals

Flats don't necessarily transpose as flats, or sharps as sharps. For example, if the accidental originally raised the note one half step out of the key, by turning a flat note into a natural, the new accidental may raise the note one half step out of the key by turning a natural into a sharp.

If you are trying to accomodate singers, your main concern in choosing a key is finding their range. Is the music you are working with too high or too low? Is it only a step too high, or does it need to be changed by a third or a fifth? Once you determine the interval needed, check to make certain this will be a comfortable key for your instrumentalists.

Example 6.1. 

A church choir director wants to encourage the congregation to join in on a particular hymn. It is written in four parts with the melody in the soprano part, in a range slightly too high for untrained singers. The hymn is written in the key of E flat. Lowering it by a minor third (one and a half steps) will allow the congregation to sing with gusto.

Figure 6.18. 

The hymn is originally in E flat. The melody that goes up to an F is too high for most untrained vocalists (male and female).

Figure 6.19. 

The same hymn in C is more easily singable by a congregation.

Example 6.2. 

An alto vocalist would like to perform a blues standard originally sung by a soprano or tenor in B flat. She needs the song to be at least a whole step lower. Lowering it by a whole step would put it in the key of A flat. The guitar, bass, and harmonica players don't like to play in A flat, however, and the vocalist wouldn't mind singing even lower. So the best solution is to lower it by a minor third, and play in the key of G.

Figure 6.20. 

(a) The key of this blues standard is comfortable for a soprano or tenor, as shown in this excerpt.

(b) An alto or baritone can deliver a more powerful performance if the music is transposed down a minor third.

Exercise 6.4.2. (Go to Solution)

You're accompanying a soprano who feels that this folk tune in C minor is too low for her voice. The guitar player would prefer a key with no flats and not too many sharps.

Figure 6.21. 

Tune in C minor too low for some sopranos voices.

Transposing instruments are instruments for which standard parts are written higher or lower than they sound. A very accomplished player of one of these instruments may be able to transpose at sight, saving you the trouble of writing out a transposed part, but most players of these instruments will need a transposed part written out for them. Here is a short list of the most common transposing instruments. For a more complete list and more information, see Transposing Instruments.

The transposition you will use for one of these instruments will depend on what type of part you have in hand, and what instrument you would like to play that part. As with any instrumental part, be aware of the range of the instrument that you are writing for. If transposing the part up a perfect fifth results in a part that is too high to be comfortable, consider transposing the part down a perfect fourth instead.

Example 6.3. 

Your garage band would like to feature a solo by a friend who plays the alto sax. Your songwriter has written the solo as it sounds on his keyboard, so you have a C part. Alto sax is an E flat instrument; in other words, when he sees a C, he plays an E flat, the note a major sixth lower. To compensate for this, you must write the part a major sixth higher than your C part.

Figure 6.22. 

(a)

(b)

In the top line, the melody is written out in concert pitch; on the second line it has been transposed to be read by an alto saxophone. When the second line is played by an alto sax player, the result sounds like the first line.

Example 6.4. 

Your choral group is performing a piece that includes an optional instrumental solo for clarinet. You have no clarinet player, but one group member plays recorder, a C instrument. Since the part is written for a B flat instrument, it is written one whole step higher than it actually sounds. To write it for a C instrument, transpose it back down one whole step.

Figure 6.23. 

(a) Melody for B flat clarinet

(b) Melody transposed for C instruments

Exercise 6.4.3. (Go to Solution)

There's a march on your community orchestra's program, but the group doesn't have quite enough trombone players for a nice big march-type sound. You have extra French horn players, but they can't read bass clef C parts.

Figure 6.24. 

Trombone line from a march

Transposition can also make music easier to play for instrumentalists, and ease of playing generally translates into more satisfying performances. For example, someone writing a transcription for band of an orchestral piece may move the entire piece from a sharp key (easier for strings) to a nearby flat key (easier for winds). A guitar player, given a piece written in A flat for keyboard, will often prefer to play it in A or G, since the fingerings for chords in those keys are easier. Also, instrumentalists, like vocalists, have ranges that need to be considered.

Example 6.5. 

Your eighth grade bassoon player would like to play a Mozart minuet at a school talent show with a flute-playing friend from band. The minuet is in C, but the melody is a little too low for a flute, and the bassoonist would also be more comfortable playing higher. If you transpose the whole piece up a minor third to E flat major, both players can hit the lowest notes, and you may also find that fingerings and tunings are better in the flat key.

Figure 6.25. 

(a) An excerpt from a Mozart Minuet in C. The upper part is too low for a flute player.

(b) Both young instrumentalists would be more comfortable playing in this key.

Exercise 6.4.4. (Go to Solution)

You've brought your guitar and your capo to the sing-along because you'd like to play along, too. Going through the music beforehand, you notice that your favorite song is in A flat. The pianist isn't prepared to play it in any other key, but you really don't like those thin-sounding chords in A flat. You can use your capo to raise the sound of your instrument (basically turning it into a transposing instrument in C sharp, D, D sharp, or even higher), but the less you raise it the more likely you are to still sound in tune with the piano.

Figure 6.26. 

Chords in the key of A flat major are not ideal for guitarists.