@formydad Gently stress to your dad how important it is to understand what doctor is saying. To that end, having someone with him who will act as a "second set or ears and eyes" can help immensely. Take notes, don't be afraid to ask for clarification or more information. I have found when we are used to talking about a subject, sometimes we assume the listener understands more than they do, or we use terms familiar to us but not to the listener. An example of that, I am a crafter, and forget a listener doesn't know what I am talking about. I don't "dumb it down", just explain it in layman terms. Hope this helps,
Ginger