I actually really enjoy the sound of a crowded room. I used to be a DJ and party organizer and a room full of happy people is a peaceful and delightful sound to me ( much unlike mouth sounds, and pouring liquids and plenty others ).

Still, picking out a single voice from a crowd is incredibly difficult for me. That wasn't always the case. I believe it started in my late 20s, which is interesting because I'd noticed around then that crowded rooms started to sound different for me. The hum of the room was more distinct.

My wife has a very distinct voice that I can easily pick out in a crowd and I sometimes wonder if that was an unknown part of the initial attraction. At the very least we can still go out and have a conversation in loud public places, which is something I can't do very well with many other people.