Re: Me and my sister recording some harp in a church
That's actually a very good question, Larry. A concert harp like this uses pedals to set the pattern of sharps and flats, as you may know, so however the pedals are set, you've always got one key signature or other, and every string will sound as part of that. There's one pedal per note name, governing the sharps and flats for every octave at once.
For example, with all the pedals set in a central position, you've got the key of C major (which is also A minor). In order to play a wrong note, you'd have to set the pedals wrong for the key you were playing in. This is of course eminently possible, particularly if there are quick pedal changes required. This is true of smaller harps too, which use two-position levers to raise the tuned pitch of each string. In this case you can have different sharps or flats in each octave, making dissonance and perhaps even chromaticism easier to achieve.