I did look on Suggestion Compendium could not see this if missed it very sorry.
Ok soundproofing few ways could add it to the mod could be upgrade mod or a block. I love some of the sounds in IC2 but other ones that go 24/7 like watermills start to bug me after a while.
Upgrade mod = self explanatory but sadly limits the use to only blocks that have mod slots.
Block = place block next to or within certain range of the block that you would like to disable sound for. Could have multiple types.