Problem with Audio broadcasting

programming flash
1

hi evetyone,

am doing a application which has two way audio interaction ,

and the code is like this

var ns_out = new NetStream(nc);
var ns_in = new NetStream(nc);
ncMic = Microphone.get();
ns_out.attachAudio(ncMic);
ncMic.onStatus = function(micFunc:Object) {
    trace("Mic Func: "+micFunc.code);
    switch (micFunc.code) {
    case "Microphone.Unmuted" :
        if (first user) {
            ns_out.publish("first", "live");
            ns_in.play("second");
        }
        if(second user){
        ns_out.publish("second", "live");
        ns_in.play("first");
        }
    }
};

the above codes are working fine and allowing both the users to talk, the problem is how to stop a particular user’s audio , i tried using ns.close(), attachAudio(null) function’s , but both didnt work, how can i solve this ???

thanks in advance.