My son is partially deaf and can only hear when I shout. So am I just not supposed to talk to him in public?

Damned if you do damned if you don't situation, no one wants to hear your personal conversations especially if they are out like at a restaurant. Shoot I hate it when people are talking on their cellphones while waiting in line at the grocery store. SO from that point I don't want to hear it, but your son has legitimate disability and I feel for that. It's just a matter of degree, of when and how you need to be aware of the fact it bothers people and everything can't revolve around your needs at the same time if you've explained the situation then you are deserved a apology from anyone making rude comments