Interesting idea. I hadn’t thought about it, but there is a difference between hearing with no background noise and hearing if there is. Sometimes see that in older people with hearing aids, but sounds (no pun intended) in your case it is not loss of hearing, but difficulty in discriminating. Again, can’t really say if psychological or neurological. Some people are better at tuning out background noise/distractions than others. Example: I hate have a TV on in the background, it pulls my attention (which of course it is designed to do), whereas lots of people need background TV to work/study. A perhaps related issue is being able to understand someone who is talking directly to you, but not being able to follow two people talking to each other. I think this is more common than we think, but mostly noticeable with a second language.