*Sigh* People people, you guys aren't using your heads here. The best solution is put the following in your AutoExec.cfg:
sv_voiceenable "0"
voice_avggain "0.000"
voice_clientdebug "0"
voice_dsound "0"
voice_eax "0"
voice_enable "0"
voice_fadeouttime "0.000"
voice_inputfromfile "0"
voice_loopback "0"
voice_maxgain "0"
voice_modenable "0"
voice_overdrive "0"
voice_overdrivefadetime "0.000"
voice_profile "0"
voice_recordtofile "0"
voice_scale "0"
voice_serverdebug "0"
voice_showchannels "0"
voice_showincoming "0"