That is exactly correct, for wind instruments at least: and in fact, some wind instruments have more than 10 holes or keys. But many combinations produce identi

That is exactly correct, for wind instruments at least: and in fact, some wind instruments have more than 10 holes or keys. But many combinations produce identical sounds, limiting the range of the instrument. The limiting factor on a wind instrument is the fact that it can only play a single note, (yes, with resonant frequencies, of course) and the length of the instrument, which determines the lowest note it can play.