Choosing a Key for a Transposing Ensemble
A student composer writes a 16-bar fanfare for a school ensemble: B-flat trumpet, alto saxophone (E-flat instrument), and horn in F. The melody sits comfortably between written C4 and C5 on the trumpet. The composer wants the concert pitch to land in B-flat major so the brass sound bright and open. After drafting, the alto saxophonist reports that her written part contains five sharps and a repeated high F-sharp that sits awkwardly under her fingers. The horn player says his part is fine but that the fanfare's climax now sounds thin because his written notes sit low in his range. The composer has one rehearsal (45 minutes) before a 6-minute performance and cannot rewrite the melody's contour, only its key and octave placement.
1. Explain how the composer should reason about the relationship between written pitch and concert pitch for each instrument, and identify the concert key that best balances the players' constraints.
Read the worked answer
Each transposing instrument sounds at an interval from its written pitch. A B-flat trumpet sounds a major 2nd lower than written, so written C sounds concert B-flat. An E-flat alto sax sounds a major 6th lower than written, so its written C sounds concert E-flat. A horn in F sounds a perfect 5th lower, so written C sounds concert F.
If concert pitch is to be B-flat major, the written keys are found by transposing up by each instrument's sounding interval. Trumpet: written C major gives concert B-flat major, so the trumpet reads C major (no sharps or flats). Alto sax: to sound concert B-flat, it must read a major 6th higher, which is G major (one sharp). Horn in F: to sound concert B-flat, it reads a perfect 5th higher, which is F major (one flat).
So the composer's instinct is correct: concert B-flat major yields friendly written keys for all three. The saxophonist's five-sharp part means the draft was NOT in concert B-flat - it was probably a whole step or more away, forcing the sax into B major or F-sharp major. Recomputing the key removes the awkward F-sharp entirely. The horn's thin climax is a separate issue: his written notes sit low, so the composer should raise the horn line by an octave at the climax while keeping the same written key. That fixes the balance without changing the melody's contour or the concert key.
2. The saxophonist's original part had five sharps. Work out what concert key the draft was actually in, and explain why this diagnosis matters before the single rehearsal.
Read the worked answer
Five sharps in a written key means B major (F-sharp, C-sharp, G-sharp, D-sharp, A-sharp). The alto sax sounds a major 6th below written, so written B major sounds a major 6th lower. A major 6th below B is D (B down to D is a major 6th). So the draft was in concert D major, not concert B-flat major.
This matters because the composer's stated goal was concert B-flat. The draft was a minor third too high in concert terms. That single error explains both symptoms: the sax was pushed into a remote key (B major, five sharps) and the horn, reading in concert D transposed to its written key of A major (three sharps), had its melody sitting lower relative to the ensemble's tessitura than intended, thinning the climax.
Diagnosing the actual concert key before the 45-minute rehearsal prevents the composer from tinkering with individual accidentals or octaves when the real fix is a single global transposition down a minor third to concert B-flat. That one move converts the sax part to G major (one sharp) and the horn part to F major (one flat), freeing rehearsal time for balance and ensemble issues rather than damage control.