text: transposition? music 101 what do you want to know about it?  transposition is the interval that notes have to be moved up or down for certain instruments to be able to play in concert with a piano or other non-transposing instrument.  for instance, the soprano clarinet and the trumpet are b-flat pitched instruments (because of the way they are built). in order for them to play the same note middle-c as the piano, you must write (or play) the note 1 step higher on their part ( in this case the d just under the treble clef).  please elaborate on your question if you need more. i'll check back.