This will improve voice quality for those who are using in game communication on our servers. Most mics will sound much better but some may sound worse, give it a try!– Added support for alternative voice communication codecs. While running a server, use +sv_voicecodec vaudio_celt to use the CELT voice codec, instead of the Speex codec which is used by default.
http://blog.counter-strike.net/index.php/2015/04/11936/