I may be thinking of another game or something, but wasnt there a feature which used to highlight who was talking on vox channel?
Sure you get the name pop up in the top right of the screen, but i seem to remember a box being drawn around the actual icon of the person talking if they were nearby - anyone know what i'm on about?
Is there a setting to turn this on / off? I found it handy when there were a lot of friendlies around - guess its not really realistic it all helps to make it fun.