It's not one big raging party town, if that is what you mean. There will be bands at some establishments and the music does tend to be loud enough to be heard outside.
If you are staying out of the town, you won't hear it anyway.
Music is part of life in any resort village.
Alcohol is as well.
You'll be just fine. Just remember it gets dark early all year long in Belize.
Go and enjoy every minute, I do and I don't drink