There are a lot of things you can use to wrap your chainstay with and protect it and quiet it down. You can buy a chainstay proctor or make one out of an old innertube but my favorite so far has been
https://www.amazon.com/3M-Scotch-Sea.../dp/B0010XFTQ6
Just put a layer of that down over top the clear stuff your bike already has from the factory. The clear stuff keeps the paint in decent shape but it doesn't do much for the noise.