by Brian Blood
A transposing instrument is a musical instrument where what is written is not what is heard, i.e. the written pitch differs from the pitch that the instrument sounds. The written pitch is actually a transposition of the sounding pitch. It should be understood that transposing instruments are not themselves peculiar, only that the convention employed when writing parts for such instruments differs from that used for non-transposing instruments where, subject to a transposition of one or more octaves, the written note is the same as the note heard.
Where the instrument has a range that does not lie within the normal clefs, the music may be written either an octave lower than it sounds (e.g. piccolo, descant recorder) or an octave higher (e.g. double bass, contrabassoon, bass guitar, guitar, tenor male voice). Although these are strictly 'transposing instruments', most authorities do not describe them as such.
|C pitched instruments (said to play at concert pitch)|
|general||all keyboards, voice, mallet percussion, and strings|
|woodwinds||piccolo, flute, bass flute, clarinet in C, contrabass flute, oboe, bassoon, and contrabassoon, saxophone in C|
|recorders||although made in a variety of sizes (and hence pitches), the recorder player reads music at true pitch and adjusts the fingering accordingly|
|brass||cornet, trumpet in C, and tuba|
As we saw earlier, much of western music uses a notation that describes the sound that is required in terms of its pitch, duration and volume, rather than what you have to do with the instrument to produce the note; i.e. this fingering on a woodwind or brass instrument, that position for a finger on a string, and so on. Using the standard western music convention the same piece of music may be played on a whole range of different instruments, e.g. violin, flute, oboe, piano, guitar, voice, glockenspiel. A musician may 'read' a piece of music without necessarily knowing anything about how a particular instrument is played.
Unfortunately, under certain circumstances and despite its simplicity, this standard convention is not always the most convenient, and alternatives have been developed that address certain problems.
It would be convenient if a player, having associated one set of fingerings with a particular instrument, could play all the sizes of the same family of instruments, where the sequence of fingering remains the same as one moves up or down a chromatic scale, even when the family members are in keys that differ from that of the instrument with which the player has been first acquainted. In this case, the player would far rather be told prompted for the fingering he or she should employ to sound any required note, than having to know what note will actually sound.
For example, the standard transverse flute is pitched in C and is non-transposing, i.e. when the flute player reads a C, the note you hear is a C.
The alto flute, which is effectively the same instrument, only longer, and therefore at a lower pitch, produces a G a fourth lower when the player uses the same fingering as he or she uses on a standard flute.
Alto flute music is transposed up a fourth - a G in an untransposed part is written in the transposed part as a C, a fourth higher. The alto flute player reading C in the transposed part fingers the alto flute exactly as if he or she were playing the written note on a normal transverse flute in C, and the required note, a G, sounds.
If the composer want an alto flute to sound a C, he or she will write an F, a fourth higher, in the transposed alto flute part.
The result is that flute players can swap between instruments without having to learn two different 'note read - note heard' conventions.
A similar approach is used for many other families of musical instruments.
For example, clarinets come in various sizes and hence pitches (A, Bb, C, Eb), but the music is transposed appropriately for each size of instrument so that the player can happily move from one to the other. The only complication is that the most common sizes of clarinet are Bb and A; this means that people tend to say 'the clarinet is a transposing instrument' which, while broadly true, is not the case for the C clarinet. On the C clarinet, the note read is the note that sounds.
Some families of transposing instruments are:
- most members of the clarinet family (clarinet in A and Bb; high clarinet in D and Eb; bass clarinet in Bb; contrabass clarinet in Eb and Bb)
- some members of the oboe family (oboe d'amore, cor anglais in F)
- the saxophone family (there are saxophones in C though, thus non-transposing)
- the trombone family is treated as transposing instruments in band scores
- most brass instruments, notably the trumpet in B flat, the bass trumpet in E flat, the bass trombone in E flat and the French horn in F.