oblivious

adjective. totally unaware of surroundings

"His face is glued to screen, totally oblivious to everything else."
"While humans are oblivious to infra-sounds, birds can hear tornadoes coming from 250-560 miles away and flee a day or two before it hits."
"I found a couple of geese wandering on the newly formed ice at our backyard, totally oblivious to the subfreezing temperature"

http://www.vocabulary.com/dictionary/oblivious