I could find no tag that fit this description best.
But if you go to the in-game menu, open up the volume tab, and reduce all three sliders, even to 0%, the environment / weather effects and some other small sounds still play at 100% volume.
You can technically go to the ffxiv configuration tool 'out of game' and disable the entire sound driver, and this works. But to adjust the game volume you have to completely leave the game.
If I'm crafting, I like to have some music playing, or if I'm partying, doing leves with friends and we want to use Ventrillo, I have to disable the sound because I can't hear anyone 'well' over the environment noise.
If you reduce all fields of volume in-game, it should 'actually' reduce all volume output.