As you have probably gathered by now, I am totally fascinated at how astute the untrained ear can be. I teach singing to "non-singers" by getting them to be sensitive to tunable and untunable intervals. Yesterday a complete novice demonstrated, instinctively how musica ficta works -- the sharps and flats not printed in the score of Renaissance vocal music, but known to represent the way the notes were actually tuned in practice. Such things knock my socks off.