Transposing instrument

A transposing instrument is a musical instrument whose music is usually written at a pitch different from the pitch that it sounds. The difference between a transposing instrument and a non-transposing instrument is only in whether or not the music is written at its sounding pitch; there is nothing about the physical construction of an instrument that makes the difference. Instruments whose music is written exactly as it sounds are said to play in "concert pitch".

Other transpositions

The other principal use of transposition arises when there is a family of instruments with differing ranges. It is desirable for these instruments all to have the same fingering for each written pitch, so that a player who wishes to switch between different instruments in a family does not have to learn new fingerings for each one.

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Instruments that transpose this way are often referred to as being in a certain key, such as the A clarinet (clarinet in A), or the F horn (horn in F). The "key" an instrument is said to be in tells how far from concert pitch an instrument's music is written. Specifically, the key given tells which note is the sounding pitch when the player reads a note written as C. A player of a B♭ clarinet who reads a C on the music will sound a B♭, while an F horn player will read the same note and sound an F.

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One example of an instrument family with different transpositions is the flutes. The standard concert flute has a range from middle C up about 3 octaves. The alto flute is a very similar instrument, but longer, and hence pitched lower, with a range starting from the G below middle C. The fingering that would on a normal flute would sound a C produces a G a fourth lower on the alto flute. If alto flute music were written at sounding pitch, flute players wishing to learn to play alto flute would have to re-learn fingerings for each written pitch.

Related Topics:
Flute - Alto flute - Fourth

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Instead, The music for the alto flute is tranposed up a fourth so that the player may play the alto flute using the same fingering for the written notes, but the resulting pitches are a fourth lower. The result of this is that the flute player can easily learn the new instrument, and can easily switch back and forth between the two (a common requirement in orchestra music) without risking confusion between two different fingering systems. The alto flute is then a 'transposing instrument in G', sounding a fourth lower than written.

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A similar thing happens in other instrument families. For example, clarinets come in various sizes and hence pitches (A, B♭, C, E♭), but the music is transposed appropriately for each size of instrument so that the player can easily move from one to the other. Expert clarinet players often use a different instrument than the transposition of their parts calls for, transposing the parts at sight instead; expert trumpet players may do this also.

Related Topics:
Clarinet - Trumpet

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In some families of instruments, the non-transposing C version has fallen into disuse; the clarinet family is one example, where only the B♭ and A members are common. Horns are another example.

Related Topics:
Clarinet - Horn

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Some families containing tranposing instruments:

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• the clarinet family (soprano clarinet in B♭ and A; sopranino clarinet in E♭ and D; alto clarinet in E♭; bass clarinet in B♭; contralto clarinet in E♭; contrabass clarinet in B♭)
• some members of the oboe family (oboe d'amore, cor anglais)
• the saxophone family (either B♭ or E♭)
• most brass instruments, notably the trumpet and French horn.

The horn is a particularly interesting case. Before valves became common about 1800, horns could only play the notes of the overtone series from a single fundamental pitch. However, this fundamental could be changed by inserting one of a set of crooks into the instrument, shortening or lengthening the total length of its sounding tube. As a result, all horn music was written as if for a fundamental pitch of C, but the crooks could make a single instrument a transposing instrument into almost any key. Changing the crooks was a time-consuming process, so it only took place between pieces or movements. The introduction of valves made this process unnecessary, but Richard Wagner (1813-1883) wrote horn parts as if crooks were still in use. Furthermore, even though an F tranposition became standardized in the early 19th century, composers were inconsistent in whether they expected the instruments to transpose down a fifth or up a fourth, especially when written in treble clef.

Related Topics:
Horn - Valves - Overtone series - Fundamental - Crook - Richard Wagner - 19th century

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There are a few families of instruments which have instruments of various sizes and ranges, but whose music is rarely or never transposed. The recorder family is one of these. The higher members of the family (alto and above) transpose at the octave. However, they are referred to as "C-fingered" or "F-fingered" depending on the lowest note, which is fingered the same on all sizes. A player may go from one C-fingered instrument to another easily, and from one F-fingered instrument to another easily, but switching between the two requires learning a new set of fingerings.

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