how can i hear people talk on xbox live can somebody plz help me i can see other people's mic icon light up but i still can't hear them so it would be nice if someone could give me some tips ...

Depending on what game mode your playing public VOIP will be turned off. Press start go to scoreboard highlight the person's name and hit create/join/invite fireteam. If you play competition under the freeplay tab you'll talk to everyone.