The Title says it all! I was thinking instead of using Teamspeak There is a specicfic plugin which makes it when you are near a player you can hear them with Microphone It might be a bit creepy and a bit like stalking BUT there is ways to setup the commands like
/talk (playername) does not matter how far away you are from them
/talk local (Talk in local chat)
/talk on/off (To turn it on or off
I don't know IF its possible to setup commands like that but dunno Tell me what you Think!