Potential signs and symptoms of a concussion include headache, dizziness, nausea, ear ringing, sensitivity to light and sounds, slurred speech, impaired memory or judgment, as well as changes in reaction time or balance.

FORBES: Safety Prevails -- In Updated Guidelines To Manage Concussions

What was interesting was that even though I could still hear most office sounds (like the phone ringing) through the ear defenders, the very act of wearing them gave off a subtle 'go-away-I'm-working' vibe that allowed others to ignore and exclude me without being impolite ... it worked for me!

BBC: The pleasures and perils of the open-plan office

Tinnitus is a medical term used to describe a ringing or buzzing noise that people can hear permanently in one ear, both ears or in the head.

BBC: Fears that music volume limits 'could be ignored'