Currently in free roam, when you press the button to show you who is in your session, it doesn't have that icon like in the mission/race loading screen next to a player's name to show that they are speaking into their mics.
This can get pretty annoying as you don't know who's speaking. This happened to me one time:
I was in a session and there were two guys with American accents talking to each other, just basically about what to do, where to go etc. Then another guy comes onto the mic and basically starts saying stuff to them putting on an American accent, "yo nigga, I think I'm American, I'm so good, you black c*nt" etc etc.
These two guys ignored him at first but he kept doing it and then it got to them. They were telling him to stop, then asked him what his ID was. This idiot then claims to be me!! I'm like "no man, that ain't me" and even called one of the American guys using the iFruit and said it wasn't me, and he's like "you sound like him, it's you!!" and then started attacking me.
If you can identify the mic people in missions/races, don't know why you can't in free roam. Or is there a way I don't know about?