To mute player that are annoying you, you have to click the guide button and go to the friends list go to recent players and find the name. Or for a fast mute press the back button on the controller while playing the game. Scroll down to the gamers name by using the D-Pad press X but it only mutes them for that game.
To make the sound go to the speakers, sign into your gamertag press the guide button, go to the settings blade and go down to preferences then go to voice, then choose speakers, headsets or both.
Speakers will allow you to hear from the TV speakers