I'm a little fuzzy on the details on where exactly the sound files are. According to the wiki that's where they should be, in the virtual/legacy folder(s). But it could be out-dated and a lot of information pertaining sound files are not up to date with version 1.7.9 I'm literally out of ideas about this issue. The best advice I have now would be to file a bug report on the official minecraft forums. Sorry I couldn't help with your sound issues.
Ah well, you know, not everything has an answer. I appreciate your help though, I really do. @kukelekuuk00 do you have any possible advice that hasn't been mentioned??
Maybe I missed this somewhere, but do you have a Ressource pack a.k.a. Texture pack installed? If you got one without sounds it is able to override your sounds from the default .jar-folder, I think. (The game wants to load a sound file it can't find in the ressource pack but doesn't use the default sounds instead.) If that is not the case however, then I have no idea. I hope this helps, and sorry if anybody posted this already but I missed it. -314 a.k.a. Pi-
