music21 (http://web.mit.edu/music21/) is in active development, and meant for music analysis and procedural generation...I don't know if it meets the numpy requirement though. From the simple glance that I gave its docs, I don't think it does...but I simply add it to the pile of "possibles", just in case I am wrong. 

I too am very interested in your question, so I am glad you asked it. I hope someone is able to come up with a good answer!