Scene: dad comes round to my house after my cold water tank overflow has been leaking for around 2 years. This is something I do not know how to fix, and cannot afford to employ anyone to do.
So finally, yesterday, he came, bearing a part that he had bought en route from the builders merchants.
Here is an excerpt from the conversation:
Dad Is this system metric or imperial?
Me Metric
Dad Because if it is imperial I have got the wrong part
Me It is metric
Dad I wasn't sure if it was metric or not, but I thought the house isn't very old, so it is probably metric
Me Yes it is
Dad Well, we'll soon find out
Me It is metric
Dad If it is imperial we will have to go shopping again
Me The house is only 17 years old; it is all metric
Dad I thought it would probably be metric, but if it isn't we'll have to go shopping again.
etc, you get the idea; it went on for at least twice as long as this. A lot of my dad's conversation comprises repeats of what he has already said. I assume he is not used to being listened to any more than I am.

And the trick once he has fitted the metric fitting to the metric system, and stopped the leak, is to cultivate a spirit of gratitude, even though to do so means stepping over the huge gulf of invisibility and negativity cast in my direction.
It is not easy, but I am trying. I must try to learn to be grateful for who and what he is, and not resent who he cannot ever be. He is just as damaged as I am, and less able to cope with it, because he does not have the same awareness as I do. It is a very long, very painful journey to learn that awareness, and it is a path he will never be able to follow. It is not for me to choose, but even if it were, I would not choose to force him to see and become aware of what he is missing. It would be, I think, too cruel. It is for me to contain.
So, having no voice is not just a childhood phenomenon, but at least we can be aware of the dynamics when we are older.