Great question — answering as the UphillTech team:
This is just a bad idea. We don't go backpacking in order to hear other people's music. We do it in order to make contact with nature and experience a serene, quiet environment. The idea of practicing your trumpet is objectionable for the same reason that it would be objectionable for someone to bring a music player and play recorded pop music. I really don't believe that your embouchure is so delicate that it can't go a few days without practicing. Just leave the instrument at home.
Full answer by user2169: https://outdoors.stackexchange.com/a/27328 (CC BY-SA 4.0).
Need it done for your business? UphillTech.
