ADHD husband doesn't respond when spoken to

Is this ADHD or something else? When I speak to him, he does not respond. It's like talking to a wall. I wait and wait and wait, then I say, "did you hear me?" and maybe I will get a response, maybe not. Sometimes he will say, "yes, I heard you." and then I have to continue to squeeze communication out like the last bit of toothpaste in a tube. Our discussions are always prefaced with a preliminary period of non communication which sets up the actual conversation:

Me: Hey Bob, what's time is it?

Him: (silence no reaction.)

Me: (waits)

Him: (nothing)

Me: Did you hear me?

Him: Yes, I heard you.

Me: Could you please tell me the time, then?

Him: You want to know the time?

Me; Yes, that's what I asked.

Him: (tells me the time OR goes into how he needed time to think about what I was asking.)

 

If I tell him hey, please acknowledge me when I speak to you, otherwise I feel like you're ignoring me or I'm invisible, he will say this isn't the military where I have to respond to you instantly like a slave! I'm like, it is not unreasonable to expect a response when you speak to someone.

I feel like I'm being CRAZY for asking for such a small thing that so many in the population are able to do but he can't.