Where are interface vanilla sounds?

Could anybody tell me, where are civ5 'interface sounds' files (like 'someone else finished wonder production!')? I tried everywhere, I have found all sounds from expansions and all music, but I never see this one :I

If I find it, I will make simple mod which will shut off these infuriating 'someone else finished wonder production' or 'unit has died' noises for myself and other annoyed players

You mean the notificationunitkilled.wav and notificationothercivwonder.wav?

I think they're in the package files. Use Nexus to extract them.

Uhm... Thats noob question but how to do that?

Open up SDK, click Nexus, then the Nexus tab, Script Browser, then click on Extract PAK (*.fpk) files and then select Run Script. After it's done extracting (which will take a very long time), it'll be located in Resource/Common.