A 20 month old child doesn't necessarily speak and some don't react to their name, either. I think you may be jumping to conclusions.
My second son didn't speak at all until he was two, then suddenly came out with complete phrases and sentences. He had ear infections as a baby, so often had his hearing checked and there was nothing wrong.
My grandson, with autism, lived in his own little world (still does, quite often) so never seemed to react. He could hear us well but usually ignored us. We had to wait until he was three for tests and confirmation of his autism.
You've voiced your concerns and that's all you can do. The parents will deal with things when they're ready - if there's anything wrong.
Vision Disturbances: "Aura" Without Headache?


