I have sort of the opposite problem with a coworker. This coworker only wants to talk through things and doesn't want to work them out on paper or a white board. The problem is that I can understand/remember almost everything I read, but have almost no ability to comprehend things that are being spoken (I suspect people are talking faster than my ability to think and parse what they are saying). I've talked to him about this to no avail. He just wants to talk things through, and then expects me to be following along and to provide insights when I have no idea what he is talking about. But if we can get it on paper or a whiteboard then I can reason about it quite easily.

I know the type of person. I usually can't follow them either (less about them being fast talkers, more about them being bad at explaining things). I found myself to usually only half-listen to what they say, and letting the other half of my mind to reconstruct the problem independently by itself. Sometimes I fail, and then I need to ask them to repeat what they just said. Other times my mental model is spot on, and I can find their problem quickly.

Try to maneuver him to where there's a whiteboard and write things down as he's talking through them: if he's reading cues, he'll slow down so that your visible note-taking keeps pace.

If that doesn't work, get him a rubber ducky [] and tell him to go talk to it if he's not willing to compromise on communication styles.

[] https://en.wikipedia.org/wiki/Rubber_duck_debugging

I worked with somebody like that once. He would get massively frustrated because he needed that back and forth to think through ideas and I was giving him nothing. I would get frustrated because I had to digest information before I could say anything about it and he wouldn't stop talking long enough for that to happen.

I had a lot of success with asking him if I could think about the problem and we could schedule a meeting in half an hour or so. He was much happier with that result because I had thought through the problem and was now able to give him the back and forth he needed. I was also much happier because I was no longer expected to come up with insight on problems I had no time to chew on.

I am often both requesting and receiving verbal problems related to the software I maintain (an Engineering simulation and analysis tool). When receiving a problem verbally is to slow the other person down by challenging any assumptions they may be making. By asking them to clarify it allows me to build a mental model of the problem before at a sustainable pace and also helps them identify a bad assumption they may be making.

When I am asking someone else to be the rubber duck I strive to highlight any assumptions I am making at each step of defining the problem. If I don't do this the other person will usually struggle to keep up.

Can you keep some paper or a whiteboard around?

You don't have to just accept doing your mutual conversation exactly as he likes it.

That is not the opposite problem. Talking through them and working them out on paper are the same thing. They are the opposite of someone doing it in their head.