Can I suggest something simple?

all you need is 17 recorded notes, 8 blown, 8 strummed, and 1 beat.
An octave each, and a beat.

I'm not familiar with sound modification through programming but speeding up the notes or slowing them down should change their sound appropriately, would that work?

that would be great, and as an addition those notes/beats could be learned and played via a tab like the spell book.

...but the most important thing in the career of bards are the lyrics and the stories they are telling with it, not the music only

* Akeera sings "My Lady d'Arbanville, why do you sleep so still?"

Agreed, but if the people have the music itself then they can role play the lyrics. So one guitar track may have many different songs.

Ok, i was looking up conversations on musical instruments, and I agree that actual playable instruments would be great. I realize that siting down in a studio and recording countless instruments for the game would be a long and tiring proses. So here is the beauty of the idea, let the Player record there own music at home onto the game.The person would have to play acoustic instruments that existed in mid evil times, but at least that would add a diverse music seen, and If some one wanted to learn that music then the creator could sell the paper to them that would allow usage.

This would liven up inns, and bring entertainment to the musical aspect of the game.
Feel free to add input