This is the setup that pro Starcraft tournaments use so that players can't hear the announcers and crowd.
(I don't have a problem with ambient conversation at, say, Starbucks, but I find myself very distracted by people talking about work stuff in the same room as me.)
They also squeezed my head which was uncomfortable after 8 - 10 hours.
Lastly, people kept trying to talk to me, which meant I had to pull them off and put them on and pull them off and put them on which was a little maddening.
The two headsets were 1) voice chat with your team 2) large 'surround sound' headphones that really signaled direction.
More recent tournaments they seem to have integrated ear defenders with headphones with Mic's on. (Previously they had 3 headsets, the ear buds for sound, the defenders then their sponsors headsets around their necks for the mic.)