Rehearsal letter

A rehearsal letter is a boldface letter of the alphabet in an orchestral score, and its corresponding parts, that provides the conductor, who typically leads rehearsals, with a convenient spot to begin at places other than the start of movements or pieces. Rehearsal letters are most often used in scores of the Romantic era and onwards, beginning with Louis Spohr.

They may also be generically called rehearsal marks or rehearsal figures, or, when numbers are used instead of letters, rehearsal numbers.

In the course of rehearsing a symphony or piece, it is often necessary for the conductor to stop and go back to some point in the middle, in order to master the more difficult passages or sections, or to resolve a challenge that the ensemble is having. Many scores and parts have bar numbers, every five or ten bars, or at the beginning of each page or line. But as pieces and individual movements of works became longer (extending to several hundred bars) as the Romantic era progressed, bar numbers became less practical in rehearsal.

For example, a conductor can tell her musicians to resume at bar 387, so that the musicians have to find the nearest bar number in their parts (e.g. 385 or 390) and count back or forward a couple of measures. Even if the number 387 is written at the appropriate bar, it might not particularly stand out. But if there is, for example, a big, bold letter M in the score and parts, it is much easier for the conductor to just say "begin at letter M". Even if the conductor were to say "one bar before letter M", that would still be more convenient than saying "bar 386". Alternatively the conductor could first say "before M..." and allow the players time to find M and then say "one bar".

In the score of a full orchestra, rehearsal letters are typically placed over the flutes' (or piccolo's) staff, and duplicated above the first violins' staff. For concert bands, rehearsal letters are placed over the piccolo's staff (or flutes'), and over the trumpets'. Rehearsal letters should appear in every part, but the conductor or librarian should check this and also make sure that they agree with the conductor's score; if they do not, the letters from the parts should be copied to the conductor's score. For typical pieces or movements of the Romantic era marked allegro, the letters A to Z can be used up, though the letter I, J or O (or all) may be skipped.

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