No need to look me up - I am here.
Oberlin does indeed seek out students who are interested in the double degree in all disciplines. In fact, the current dean of the conservatory is an alumnus of the Oberlin double degree program. Over a quarter of the entering conservatory students this year are enrolled in the program and there is widespread institutional support for it. There are reported to be a small number of applied music teachers who do not want their students in the double degree program, so it is still a good idea to ask about it when taking a sample lesson.
My daughter is no longer a double major. She decided to give up the math degree and work on music full time so that in addition to classical bass she would have time for jazz bass and viola da gamba lessons and an ethnomusicology minor. From what I hear, the conservatory has overall acceptance rates around 30% (as usual, rates are much lower than that for flute students and female vocalists). I understand about half the people in the double degree program eventually drop one side or the other, but having half complete the program is still a whole lot better than the completion rate at most other schools. As mamenyu says, it can be done in four-and-a-half, or in rare cases even four years with lots of AP credit and perhaps some summer study elsewhere, but five is the norm and it is very doable. Financial aid is good for up to five years, is not gapped and is usually weighted much more toward scholarships and grants than loans.
College Board reports that the admission rate for the college is also about 30%, but the median high school GPA appears to be around 3.6 and the median SAT somewhere around 2050. In addition to grades and test scores, they take the "Why Oberlin?" essay pretty seriously.
One thing that my daughter has really liked there is the Co-op system. She lived in co-op housing for two years and has eaten in co-ops all four. As a result, she has learned quite a bit about all aspects of preparing a meal for seventy or eighty people and is head cook for at least one meal per week of that size. Moderator's Note: BassDad's paragraph above about Co-ops has been copied to start a new thread: "Co-ops" = OSCA = Cooperative housing or dining options
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