how should I call “someone who is unable to hear or speak” politely?
I understand that you want to know how you should refer to someone who can’t hear or speak. That’s a good question.
Technically speaking, a person who can’t hear is deaf and a person who can’t speak is dumb. So, you could simply say: “He is deaf and dumb”.
Some people would say “He’s a deaf-mute.”
But I understand that deaf people who also don’t speak (because they’re deaf) prefer to be called just “deaf”.
So, it might be most polite to just say: “He’s deaf.”