A transposing instrument is an instrument that is not constructed in
the key of C. Therefore, when a concert (middle) C is played on these instruments, it is actually another
note.
Some instruments transpose by
octave; some by smaller,
diatonic intervals; and some instruments don't transpose at all. Instruments that
transpose by less than an octave are considered to be in a different
key. As a
composer or
arranger, a good way to remember common
transposition method is "to hear its key you must write a C."
Common transposing instruments and their keys are:
This is by no means a
comprehensive list. The transposition of an individual instrument either should be or will eventually be incorporated into that instrument's individual node.