@bopper It is not necessary for her degree or career. However, one difference I found between schools is how “open” some departments are about non-majors taking classes. At Tulane and Tulsa, both private schools, it seemed that all students could take music classes whether they declared a music major or not. At OU, you can take music for non-major classes. If you declare a minor, it opens up several more classes. To take the full list of courses in the music school, you must audition for and declare a major. This was actually one of the criteria that almost had my daughter attend Tulane or Tulsa instead of OU.
If she could just take music classes, I don’t really think she would be asking to double major in music. Choirs, piano and voice lessons are available to non-majors at OU…she just can’t take other music courses (music theory, musicology, language diction, etc.) that she wanted.