All such sounds are stored in SoundEntries.dbc. You can find name and location of file you need there. Which MPQ... most likely some from Locales, but I am not sure.
There is http://wowdev.wiki/index.php?tit ... Sounds.dbc, http://wowdev.wiki/index.php?tit ... ounds2.dbc, http://wowdev.wiki/index.php?tit ... bClass.dbc and http://wowdev.wiki/index.php?title=Material.dbc which defines the sound idsAnd there was http://wowdev.wiki/index.php?tit ... ookups.dbc at some point