Editing Transposing instrument (section)

=== Reconciling pitch standards ===

In Germany during the Baroque period, instruments used for different purposes were often tuned to different pitch standards, called ''Chorton'' ("choir pitch") and ''Kammerton'' ("chamber [music] pitch"). When playing together in an ensemble, the music of some instruments would therefore be transposed to compensate. In many of [[Johann Sebastian Bach|Bach]]'s cantatas, the organ part is notated a full step lower than the other instruments.<ref>{{cite book|author=Laurence Dreyfus|author-link=Laurence Dreyfus|title=Bach's Continuo Group|year=1987|publisher=Harvard University Press|location=Cambridge, Massachusetts|isbn=0-674-06030-X|page=11}}</ref> See [[Concert pitch#Pitch inflation|pitch inflation]].

Some present day early-music ensembles combine instruments tuned to A415 with instruments tuned to [[A440 (pitch standard)|A440]]. Since these pitches are approximately a [[semitone]] apart, the music for one set of instruments may be transposed to match the pitch of the others. Modern builders of [[Basso continuo|continuo]] instruments sometimes include [[Organ console#Keyboards|moveable keyboards]] which can play with either pitch standard.<ref>{{cite web|url=http://www.hpschd.nu/tech/kb/trans.html|title=CBH Global Harpsichord Technology|author=Carey Beebe Harpsichords Australia}}</ref> Some harpsichords are made with a mechanism that shifts the keyboard action right or left, causing each key to play the adjacent string. If A4 is tuned at A415, that key can then play either the A{{music|#}} at 440&nbsp;Hz or the A{{music|b}} at 392&nbsp;Hz. The top or bottom key on the instrument will not produce sound unless the builder has added extra strings to accommodate this transposition.