Hullo :)
Record your voice or whatever, then convert it into .ogg ( i use DBPoweramp (
http://www.dbpoweramp.com/))
lets call your recording "record1"
Put it in its .ogg form into your mission directory (docs\arma2\missions\mission name)
then create a description.ext in the same place.
in this file put...
class CfgMusic
{
tracks[]=
{
record1
};
class record1
{
name = "record1";
sound[] = {\record1.ogg, db+0, 1.0};
};
};
save it then load your mission in the editor and create a trigger, in the bottom left corner of the trigger page click on "effects" then under "track" it should be at the bottom of the list.
And there you go, you can use that for voices and music :)