Don't give up. Find out why they are against it and stay patient and calm while speaking to them about it. I thought my son was crazy! He is a viola player...why would he want to be in a drum corps?
My son was you last year. I had very little idea what drum corps was until he asked me to take him to the Orlando show to see a friend perform who was in the HNC guard. I sat and watched and even enjoyed myself, all the while wondering why all these people around me were so fanatical about really loud marching bands.
After a year of marching season, winter guard and drum corps auditions, my son is having the time of his life and I could not be more proud.
What was his secret? He tricked me! No, seriously, he took it one step at a time and as I watched him overcome each barrier, or achieve another goal along the way, I started to hope for it for him.
I now know that they are NOT really loud marching bands, they are so much more!
Good Luck!