Jack Campin is quite right (30 Mar 12 - 07:21 AM )about this. What we call the pitch of the note an instrument produces, and how it's represented in written music, is all a matter of convention. It's giving pitches names that causes problems. If music is read as a series of intervals, which in any case makes more sense harmonically, the problem sort of disappears, so long as the instrumentalist is familiar with their instrument. Singers do this as a matter of course. they (with apologies to those blessed, or cursed, with perfect pitch) don't sing, for example, a D followed by a (higher) A, simply two notes a fifth apart (although possibly with reference to a pitch provided by a fixed tuned instrument; and without going into complications caused by temperament).