You have to use Codewalker to do this properly. Using a combination of Codewalker's ambient audiozone map and Codewalker's .rel editing capabilities, you can either add or remove individual sounds. And you need to do that, since many zones use several layered individual sounds.
To get started go here, go here and download the latest Codewalker version :
You will obviously have to learn how to do this gradually, so experimenting will be a part of your process, but you can always ask for help in #fix-my-mod. Or you can hit me up on Discord : Modifiver#1744
I might take a while to get back you, but eventually I will, heh.
I hope this will help you a bit.