Most band and wind ensemble brass parts are written for Bb trumpets and F horns. Consequently, they do not require performers to transpose during performance. Likewise, modern composers for beginning orchestral music will typically provide parts for their music in which students do not need to transpose. More advanced orchestral music will often require players to transpose the written notation in performance.
Case 1: A high school trumpet player is playing in a good school orchestra. The director has programmed Beethoven, op. 84, Overture to Egmont. When the player looks at her part, the first measure on the page looks like this:
Musical example indicating use for a trumpet in F.
Chances are, she won’t have an F trumpet in her case to play the notation as written. Nor would the sound quality of that instrument fit the piece. Remember that she needs to adjust her playing, i.e. transpose her instrument, to the part. Assuming she is using a C trumpet as is typical in orchestra contexts, the transposition is C (trumpet) to F (part), or up a Perfect 4th. As a result, she would need to play a top line F to produce the correct pitch:
Musical example showing written notation for F trumpet and note that should be played on C trumpet.
Played on a Bb trumpet, the transposition would be Bb (trumpet) to F (part), or up a Perfect 5th:
Case 2: Sitting in that same orchestra, the principle horn player would see this on his page for the Beethoven overture:
Musical example indicating use for a horn in F.
Unlike the trumpet player, he does not need to transpose since his instrument is keyed in F and the part is written for an F instrument. Whew! But when he looks over at the second horn player’s part, he sees:
Musical example indicating use for a horn in E-flat.
The player on this part would need to transpose from F (instrument) to Eb (part), or down a Major 2nd: She would therefore finger and play a 3rd space C.
Case 3: The player on the Horn III part in Brahms’ Academic Festival Overture also needs to transpose. The part is written for horn in E. An F horn player would need to transpose each note down a minor 2nd in order to play the correct pitches. This excerpt is taken from the middle of the piece:
Musical example showing written notation for horn in E against played pitches for horn in F.
Case 4: The trumpet part to Samuel Goldenberg und Schmuyle in the Ravel orchestration of Moussorgsky’s Pictures at an Exhibition is most often played on a piccolo trumpet to facilitate playing in the high tessitura. Although most players and directors will not encounter the original part in school ensembles, the example illustrates a fairly common transposition principle for advanced trumpet players using a piccolo trumpet. The use of the Bb lead pipe would make for some awkward fingerings, so players use the A lead pipe for the piece.
The part is written for C trumpet, so the transposition is A (piccolo trumpet) to C (part). Piccolo trumpet parts are written down the octave from where they sound, so the transposition is down a Major 6th rather than up a minor 3rd. One trick trumpet players may utilize in this case is to read the original as bass clef without transposing but being mindful of accidentals.
Musical staves comparing notation for C trumpet and piccolo trumpet in A.