This is odd. In all previous editions of the calendar, it says that the only prerequisite for any of the Ensemble Performance courses is "Successful audition required". Indeed, I knew several students who were not music majors yet were in the Orchestra/Choir/etc. Only this year has the prerequisite been changed to "Registration in a Music program". If that's true, I think it's a pretty bad decision on SOTA's part.
You may want to e-mail the director of most of the ensembles, Dr. Keith Kinder (
[email protected]), and ask him. By all accounts he's a great guy, and will be able to answer this more definitively.
I can tell you that in the past, you had the choice to either do the band/choir as a credit course or as a non-credit extra-curricular, but as already mentioned, it's a pretty easy credit if you're competent with your instrument. If you already have 30 units and you want to take it for the credit, I think you just have to go to your faculty's Associate Dean's office and request to overload the semester (this sometimes is even pre-authorized - try it on SOLAR and it may just work). This would only apply if you can be in the ensembles as a non-music student this year, so make sure you inquire about that!