How turn off in-game voice in Dungeon Siege III

Do you happen to use other VOIP programs like Teamspeak or Ventrilo when playing games? If you play Dungeon Siege III you may find it annoying that by default volume activated VOIP is on by default and searching the options menu will reveal you can't actually turn it off!

Fortunately, there is a way to do it, even though it might not seem to be the case at first glance. When a friend joins your multiplayer game, right-click on the green circle next to their name and select Mute Player.