Instruments whose music is not notated at its sounding pitch but transposed up or down by a specific interval. Transposition is reckoned relative to the pitch C, so that an instrument ‘in F’ sounds F when C is notated. The intention is to maintain the same fingering etc among instruments of a similar kind but of different pitch.

In the woodwind, an example is the english horn, pitched a 5th below the oboe (in C). The same fingering for both instruments will produce sounds a 5th lower in the English horn; its music is therefore notated a 5th above sounding pitch so that the player can read it with the same fingering. This principle applies to virtually all types of clarinet, the alto flute and piccolo, the double bassoon and the saxophones. With brass instruments, the notes of their harmonic series have traditionally been written in the key of C whatever the pitch of the instrument. Typical transposing brass are the horn in F and E♭ and the trumpet in B♭, A and D. Among the few transposing bowed instruments the most common is the double bass, written an octave above sounding pitch, as also, usually, is the guitar's.

The Concise Grove Dictionary of Music. Copyright © 1994 by Oxford University Press, Inc.. All rights reserved.