When a singer asks to try a song “in a different key,” she is transposing the music. In effect, she is shifting the pitch of all the notes in a melody by the same degree, higher or lower, to match her vocal range. The relative change from one note to the next successive notes in a melody, however, remains the same. There are several helpful tricks and techniques to transpose music, and which one works best for you may be partly determined by your specific instrument.
In transposing a song from the key of C to E, the key of E differs from C by a higher pitch interval of two whole notes. The chromatic scale consists of the notes C-D-E-F-G-A-B and the familiar piano pattern of half-note black keys in between them. Transposing the song to the key of E is as easy as changing each note by the same pitch interval, two steps up.
This formula to transpose music is so simple and straightforward that many electronic instruments, and interfaces such as amplifiers, come equipped with the ability. With the push of a button or turn of a knob, you can transpose music without any mental effort at conversion. Most vocalists also exert little effort at successful transposition. Their brains will have memorized a melody as a sequence of pitch changes. To sing in a different key, your main task might only be to find the correct pitch for just the first opening note.
Some experienced instrumentalists naturally gifted with accurate pitch recognition can also transpose music with the ease of a vocalist. Most musicians simply practice a few, primarily visual, tricks of the art. One way is a concentrated, continual effort to mentally move the individual notes on sheet music according to the transposition formula. Musicians will usually become proficient to some degree at reading musical changes in interval between one note to the next. You might also adopt this method, needing only periodically to re-orient yourself by converting a note here and there within the musical score.
Another closely related visual technique is not to move the notes, but rather to mentally move the entire five lines and four spaces of the staff on which the notes are written. If you can achieve this trick of self-deception to see the lines and spaces in your head contrary to what you see on paper, it can be a very effective method of transposing music. Whether you mentally shift notes, or the background staff, one critical information you must always keep in mind throughout the musical piece is the signature of the new, target key. This will ensure that you play all the correct sharps and flats for a successful transposition. With some instruments, such as the piano and harp, a musician can transpose music with minimal effort by shifting her fingers’ home position to the new key signature.
Piano, harp and a few other instruments capable of playing two or more notes at the same time, called a chord, have an added difficulty at transposing music. Take, for example, a chord on a piano consisting of five notes. It is difficult to instantly calculate mentally how to shift each note into a new key. In order to transpose chords, most of these instrumentalists must learn to recognize and name chords as specific patterns of spacing and fingering. You might be taught to identify chords numerically, so that, for example, a minor third chord in the key of C has the same configuration of notes in the key of E, simply differing in both written and keyboard positions.
One instrument that employs a unique tool to transpose chords is the guitar. A clamp called a capo is attached to its neck to shorten, and thus increase each of its strings’ pitch in half-note intervals. The guitar strings are effectively re-tuned to a new key. There are a few other similar instruments designed with the capability of being manually tuned for transposition into different keys.
Other instruments, however, can only be manufactured in just one single key. Many orchestral and brass band instruments fall into this category. To be able to play a variety of musical scores in different keys, you may have no choice but to develop the skill of transposing music. It is common for the orchestral sheet music for these instruments to simply be re-written in their respective keys, sparing the musician from the extra mental effort and minimizing the possibility that errors in transposition will occur.