You can actually figure out how a double major might work, per school. Look at major and minor requirements, often listed on websites. Also look at gen ed/distribution requirements. Most schools have 10 classes for the major, so 10/40 classes total and 30/120 credits. This varies (some schools give 3 credits per class and some 4).
Obviously schools like Brown or Amherst, that have no gen ed/distribution requirements, leave more room in your schedule for two majors. But you still have to deal with labs and rehearsals and various other conflicts that could extend the time it takes to do a double major.
There ARE programs intentionally set up for people who want to do music and science. Carnegie Mellon’s is an example. But that is not to say it isn’t difficult and there aren’t other good options for what you want to do.
I also think it can be helpful for music and science to be on the same campus, which isn’t always the case, even when they are both in the same university or college.