A music transposer is a computer software program that modifies pitches or chords into new keys. The term can also refer to a professional musician who changes the key of a pitch or chord set by hand. The programs allow musicians to ascertain how to play a piece in a new key if they cannot do the transposition themselves, or want to speed up the manual transposition process.
When referring to a computer program, music transposers require the user to input basic data about the notes and chords that need to be transposed. This means the person entering the data has to have a fundamental ability to read music and do simple harmonic analysis. Once the program has this information, the user indicates how he would like to modify the music.
One type of music transposer not distinguish between keys, working entirely on the basis of intervals. For example, the user could type in a chord progression and tell the program to raise everything by the interval of a third. This allows the user to ascertain what pitches to play very quickly, but it does not provide the user with a key context. For example, if the user entered a C major chord using the notes C, E, and G and transposed them up a fourth, the result would be an F major chord with notes F, A and C. An F major chord is found naturally in the keys of C, F, and Bb major, so the user would have to understand how the chord fits into the overall mosaic of the piece to determine which key is appropriate.
A second type of music transposer has the user indicate the original key of the piece in addition to the notes or chords. The program then requires the user to pick the key to which he wants the music changed, such as Eb to Bb. The advantage of these transposers is that they require less knowledge of specific interval relationships and show a clear relationship from one key to another. Some programs have the option of transposing either by interval or by key, which most people prefer.
The most advanced music transposers are part of complex, full-scale composition programs. They work on the same basic principles of interval or key transposers, but the musician uses QUERTY or music keyboard-entered midi pitch assignment commands rather than simple text as the input. In other words, the programs can create actual sheet music the user can print off or save to a digital file. The user usually can select all of the measures entered and then use the transposition tools in the program to create a "new" version of the music in seconds.
When referring to an individual who transposes music, a music transposer usually is commissioned to transpose a specific work a musician needs. Some transposers write out the music note by note, but with the advances in digital technology and the need for clean, quickly-reproducible copy, this is rarely done by professionals. Most transposers use computer transposers to complete their work. "By hand" transposition usually occurs when the music is needed in a hurry, the musicians do not have access to a software transposer and there is no expectation of needing the music in yet another key.
People who transpose music on a regular basis usually work for music publishing companies. In addition to entering original music data, their job also involves formatting the music and adding necessary details such as dynamic and tempo instructions. Once the music is transposed, the company can reproduce the transposition and market it. Although this is where transposition is done with the most frequency, any trained musician with a theory background should be able to transpose a musical work.
Music transposers are useful in the arts because they allow people to modify music for different instruments or voice types. For example, if a soprano wanted to sing a song originally intended for alto, she could use a music transposer to determine the pitches or chords in a key more appropriate for her range. This makes more music accessible to more musicians and are handy for teaching or testing music theory knowledge.