Is there a way to use different languages for the voices in-game?

If you want just voices changed while still keeping english text http://lexwah.com/lvoc/ Dyrus used to use it, and Riot has unofficially said they won't ban for it. The only thing support told me when asking about it is it might corrupt the client, and you use it at your own risk (if you do get banned, it's on you). It's nice because you can choose voices for individual champions, so you can have French Fiora, Korean Ahri, and Czech Braum, for example. As far as I'm aware, all lvoc does is change the voice files to the official Riot files from whatever region you select, so there shouldn't be any problem. I've never heard of someone getting banned for using only lexwah, some people have gotten banned while using it as well as other 3rd party programs though.

I wish Riot would let us just choose our preferred languages without having to use 3rd party programs or altering files, because I definitely prefer it. I just don't use lvoc anymore because it's not worth the risk to me, however small that risk might be.