[Cthulhu_]

There's a lot of people that have this; I'm sure there's a formal diagnosis for it, but the people I know have sensory processing disorder, a co-morbidity of ADHD/autism, where they get overloaded in too noisy spaces, or as you describe, are unable to isolate individual voices in a loud space - to be fair, I think most people just pretend they can hear each other in areas like that.