On Transposition...

Doesn't everyone love transposition?

Transposing in this case is taking an existing piece of music and moving it into a different key, e.g. taking the first prelude of Bach's Well Tempered Clavier (which is in the key of C major) and moving it into a different key, such as D major. For those that have some pitch discrimination and know the sweet aromas of the different pitches, transposing into a different key will produce a striking change in the flavor of the piece.

But this isn't the reason we transpose. Usually we do so for practical reasons:

• We transpose a piece down to assist singers that have trouble with the range...
• We transpose a piece up to give it added intensity.
• We transpose themes during improvising.
• We transpose subjects when improvising fugues.

I heard Cameron Carpenter perform Bach's Toccata in F major BWV 540 in the key of F# Major and then tried it myself. It was a totally different tactile experience; it seemed to breathe new life and challenges into that piece that I had heard so many times before. If you'd like to hear the Pipedreams program, click this link: http://pipedreams.publicradio.org/listings/2012/1238/ 

The awkward part of transposing is that when you travel to a different key on the keyboard, you change to a completely different pattern of black and white keys, so you can't just move your hands over a couple of spaces. There actually is an instrument where this is possible:

Since those of us in the conventional world don't have it so easy, we have to come up with other methods, and there are a few. One can do it by ear, or one can do it by manipulation of their sight-reading skills.

1. The most direct and honest way to do it is by ear. If all the melodies, chords, and relationships are known well enough, and these relationships are understood in other keys as well, it's just a matter of reproducing those melodies, chords, and relationships in a new key. If you have unlimited time to learn the piece through and through, this is one way to go. But if you have less time and can't pick it up by ear instantly, you have to resort to paper.
2. The first way one is likely to try is by trying to imagine the notes on the page being a step or a skip higher than they appear, as well as mentally changing the key signature. This is more of a 'brute force' approach since it's a lot to hold onto in your mind. Also, it becomes more difficult the farther one transposes from the original key. There is a better way, but you're not going to like it...
3. Substitution of clefs. Instead of being satisfied with the two main clefs in use these days (Treble and Bass), the elder composers used a different clef for each voice type so as to minimize the use of ledger lines. Instead of two, we have seven: Treble, Soprano, Mezzo-Soprano, Alto, Tenor, Baritone, and Bass. They have middle C on the line above the staff, the 5th line, the 4th line, the 3rd line, the 2nd line, the 1st line, and the line below the staff, respectively. For example, if you want to transpose everything up a step, then substitute an alto and mezzo-soprano clef for the treble and bass and add a couple of sharps. Or if you wanted to step down, substitute a tenor and alto for the treble and bass. Of course, this means learning to read all clefs fluently.

Different methods are used for different situations, as can be seen by the Transposition question on the AGO exams. 

On the Service Playing exam, the candidate is required to play two stanzas of a hymn (chosen in advance by the candidate)  in two different keys (chosen by the one administering the test that moment) no more than a Major Second away from the original key.  This means that the candidate can practice the four possible transpositions for as long as they want, using any method they wish. Any way that gets it done will work.

On the Collegiate exam, the candidate is required to transpose a passage of music no more than a Major Second in either direction. The candidate doesn't know the passage of music until he gets into the room, but he has 20 minutes to sort it out, along with the Harmonization and Improvisation questions. Maybe enough time to learn by ear, but maybe not. It's plenty of time to double check the accidentals and try it out a few times transposing at sight. If you want to just imagine the notes higher or lower on the page, that could work since you have a little time to woodshed. 

On the Associate exam, the candidate must transpose a passage of music not more than a Major Second in either direction. We start getting serious here, since there is no preparation time. You are allowed, however, to play the passage through once in the original key. This can help verify that what you 'heard with your eyes' is actually correct. Clef substitutions would be great for this, but note movement could also get you by. 

On the Fellowship exam, the candidate must transpose a passage of music not more than a Major Third in either direction. The candidate must transpose at first sight. At this level, probably all of the clefs are familiar to the organist, and the eyes probably already know how the passage should sound, so the ear can guide as well. Even if it's an atonal mess, the paper methods of transposition should be quite adequate to the task. 

As we can see, knowledge and proficiency of all of these methods prove their usefulness when they are combined, ear training and typographical manipulation. Transposition is used for practical live music-making situations, so the desk composer has little need for these keyboard skills. However, a great organist would be hampered by not being able to adapt in this fashion. After all, that is one of the hallmarks of a great musician, adaptability. A real musician makes music actively and intelligently, not by rote. 

(Sanctus, from Bach's B minor Mass - 2 soprano clefs, 2 alto clefs, a tenor clef, and a bass clef)