A Dictionary of Music and Musicians/Transposition
TRANSPOSITION, change of key, the notation or performance of a musical composition in a different key from that in which it is written. When it is said that a piece of music is in a certain key, it is understood that it consists of the notes of a certain scale, and that, except chromatic passing-notes and suchlike melodic changes, no note can be employed which is not a part of that scale. Each note of the composition therefore occupies a definite position as a degree of the scale in which it is written, and in order to transpose a phrase, each note must be written, sung, or played a certain fixed distance higher or lower, that it may occupy the same position in the new scale that it held at first in the original one. Thus Exs. 2 and 3 are transpositions of Ex. 1, one being a major second higher, and the other a major second lower; and the notes of the original phrase being numbered, to show their position as degrees of the scale, it will be seen that this position remains unchanged in the transpositions.
Original Key C.
Transposed into D.
Transposed into B♭.
It is, however, not necessary that a transposition should be fully written out, as above. By sufficient knowledge and practice a performer is enabled to transpose a piece of music into any required key, while still reading from the original notation. To the singer such a proceeding offers no particular difficulty, since the relation of the various notes to the key-note being understood, the absolute pitch of the latter, which is all that has to be kept in mind, does not matter. But to the instrumental performer the task is by no means an easy one, since the transposition frequently requires a totally different position of the fingers. This arises from the fact that in transposition it often happens that a natural has to be represented by a sharp or flat, and vice versa, as may be seen in the above examples, where the B♮ of Ex. 1, bar 2, being the 7th degree of the scale, becomes C♯, which is the 7th degree of the scale of D, in Ex. 2; and again in bar 3, where F♮, the 4th degree, becomes E♭ in Ex. 3. The change of a flat to a sharp, though possible, is scarcely practical. It could only occur in an extreme key, and even then could always be avoided by making an enharmonic change, so that the transposed key should be more nearly related to the original, for example—
Hence it will not suffice to read each note of a phrase so many degrees higher or lower on the stave; in addition to this, the relation which every note bears to the scale must be thoroughly understood, and reproduced in the transposition by means of the necessary sharps, flats, or naturals; while the pianist or organist, who has to deal with many sounds at once, must be able also instantly to recognise the various harmonies and modulations, and to construct the same in the new key.
The faculty of transposition is extremely valuable to the practical musician. To the conductor, or to any one desiring to play from orchestral score, it is essential, as the parts for the so-called 'transposing instruments'—horns, trumpets, clarinet, drums—being written in a different key from that in which they are to sound, have to be transposed back into the key of the piece, so as to agree with the strings and other non-transposing instruments. [See Score, Playing from, vol. iii. p. 436.] Orchestral players and accompanists are frequently called upon to transpose, in order to accommodate the singer, for whose voice the written pitch of the song may be too high or too low, but it is probably extremely seldom that transposition takes place on so grand a scale as when Beethoven, having to play his Concerto in C major, and finding the piano half a tone too flat, transposed the whole into C♯ major!
Transposed editions of songs are frequently published, that the same compositions may be made available for voices of different compass, but transpositions of instrumental music more rarely. In Kroll's edition of Bach's Preludes and Fugues, however, the Fugue in C♯ major in vol. 1. appears transposed into D♭. This is merely an enharmonic change, of questionable practical value, the sounds remaining the same though the notation is altered, and is only made to facilitate reading, but the change into G of Schubert's Impromptu, op. 90, no. 3, which was written in G♭, and altered by the publisher, was doubtless designed to render it easier of execution.