This belongs over at https://github.com/ValveSoftware/halflife
or tell me how to back normal voice, which was before update..
Well, had you looked in the right spot, you'd have noticed ValveSoftware/halflife#743 with the explanation as to why there's no cvar for the codecs. Information on Steam's voice protocol is found here: http://store.steampowered.com/news/5100/
Yeah, Valve have said they moved CS (et al) to Steam’s voice chat and the old voice support has been removed, closing.
Nothing extracted yet.
I think you should add cvar for chosing voice codec which you want to use old or new, because Lot of people deleted the update, and people who updated can't understand them. :/