If you're in a multiplayer game, but other people in your party aren't, you can still talk to them all.
- To talk to only the players in your game, press the Xbox Guide button and select Party, Party Options, Chat Channel, Game Chat.
- To talk to people who are playing a different game or no game at all, press the Xbox Guide button and select Party, Party Options, Chat Channel, Party Chat.
- To mute the voice of an individual player, press the Xbox Guide button, select Party, select the player's Gamertag, and then select Mute."