I don’t know if it will help, but if going to a doctor is something he resists, an alternative depending on where you are might be to go to Costco and get a hea

I don’t know if it will help, but if going to a doctor is something he resists, an alternative depending on where you are might be to go to Costco and get a hearing test, and buy a hearing aid from them. Hearing aids are also available over the counter in the US and I haven’t tried them. My understanding is that you need to do the hearing test yourself and they guide you through it. I can’t tell from your description if it’s anything wrong with the hearing aids or it’s about getting them adjusted properly. Feedback will happen even with pricey hearing aids, but a decent pair will automatically cut out before it gets too bad, and it should go away if you have them in your ears far enough.