I'm a long term introvert because of hearing problems. It's been much later in life that I realised I had a problem with my hearing and got hearing aids, which help, but don't fully cure the problem.
When I was a teen, I thought it was normal not be to able to hear/understand the lyrics of a song, or not to be able to hear other people talking at a loud event such as a party or disco. My default become just to smile and nod when someone was trying to talk to me. It wasn't necessarily all about it being loud either, sometimes I couldn't cope when in a group of people all talking at pretty normal volume - couldn't "tune myself in" to anyone, so just sat there silent and disengaged when everyone else to chatting away. I also got bad headaches etc in loud places and would often have to excuse myself and leave early.
I was too young to understand at that time that it was all about my hearing problems. I got into the behaviour/habit of being pretty anti social. Even at work, I hated offices with several people in as I couldn't concentrate with the perpetual background noise. I was fine in a 1-2-1 situation with other staff or clients, but I'd struggle in even a small meeting with just 3 or 4 people. I just never realised it was because I could hear one other person clearly in a quiet place, could concentrate on what they were saying, and inter-act properly, which are things I couldn't do with more people.
I now know it was all down to the hearing loss and I'm starting to build up social confidence again, now that my hearing aids improve the problem. Still not good in loud situations, such as a big party or football match etc where there's lots of people talking around me and background noise, etc., but I'm getting better at relatively smaller/quieter groups where I can actually hear what they're saying most of the time and can participate.
Because I could hear people on a 1-2-1 basis, it never twigged to me that I had a hearing problem.