Music scores, whether orchestral, concert band, big band, or a pop chart etc. typically contain a variety of differently pitched instruments. Because factors like instrument length, size and acoustical properties affect each instrument’s range / tessitura, certain instruments need to be written transposed, in a different octave, or both to produce pitches in common with other instruments.
This system of written pitch notation allows the music to remain largely within the staff for each part as well as the transposing score. Instruments written in a different octave than where they sound are referred to as octave-displaced instruments.
Additionally, it is common practice in Concert Scores to show octave-displaced instruments at written (rather than concert) pitch. This allows these instruments to be notated largely within the staff. (For Finale users, more on this later.)
TRANSPOSING INSTRUMENT TYPES
Regardless of whether a pitched instrument produces its sound by vibrating metal, membranes, strings or air, it falls into one of the following four transposition / octave displacement types:
more >> “Concert Pitch, Transposing and Octave-Displaced Instruments : A Prelude”



