Clearly, the aubionotes default pitch detector is quite sensitive when analyzing vocal audio. It throws in a lot of in-between notes, which makes the resulting midi output a bit "tremolous".

I think now is the time to read more about the different pitch detection functions, and/or other filters to try to make the pitch detection algorithm less sensitive to small pitch variations, or else maybe even implementing my own pitch detection algorithm.

So far it has been a lot of fun!