[aptimpropriety]

Small nitpick: my understanding (perhaps moreso in more sound-dependent FPS) is that pro gamers are already sound shielded.

The two headsets were 1) voice chat with your team 2) large 'surround sound' headphones that really signaled direction.

[eterm]

Definiately not the case for league tournaments. In the spring split of EU LCS they wore 3M Peltor ear defenders over small in-ear buds for their actual sound.

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.)