I think that Cvar is for "Killstreak option",
Multikill,Monsterkill,Killingspree,etc......not "Round start,HS,knifed....... ;) hope you understand!
Code:
ut_killstreak_advanced (default 3) - enable/disable kill report, hudmessages
1 = Only HudMessages <<= Killingspree,multikill,megakill messages
2 = Only Sounds <<= Killingspree,multikill,megakill sounds
3 = Sounds and HudMessages <<= both
**Another number disable this event