Air_i don't think its possible to individually mute sounds, but you could replace the sounds of everything with a silent audio file. i'm not sure where i found them, but in my custom folder i have some sound files that replaces the audio of the end of round applause, the announcer, and the dominations with silence.
they're vpk files, i don't know how to do this though.
i assume this won't work on sv_pure 2 servers right?