Wow, maybe this explains why I can't hear anything in large groups of people.
For a long time I believed that I can't hear anything in large groups because I'm introvert (which I am) and large groups exhaust me. Turned out to be hearing problem.
And the thing is that I never had a feeling that my hearing is poor. But some day I got tinnitus that did not go away over time, and after some tests I learnt that I'm almost deaf for high-frequency tones. It impairs speech understanding, especially when there is a lot of background noise like on busy street... or family gatherings.
The filter limits unhelpful input into my left ear, which for me is conflicting input in voice range and high-pitched loud noises.
I was instructed to wear it for classes and meetings and to sit to the left of the main speaker when possible.
I haven’t worn it in years, but I credit it with a higher GPA and a few friendships that might have struggled to form if I hadn’t been able to hear well enough to converse.