Thank you for the tips, you make a good point. I realized that I tend to be a lot less responsive than I think I'm being. Usually when I listen I get very quiet, I actually notice some of the 9s wait for a response from me while I'm just waiting for them to go on. :/
As for asking specific questions, I'll make sure to make an effort but do 9s feel intruded upon when someone asks a lot of questions? Because I'd like to ask them many questions but I always feel nosy doing such things (it's probably the only thing stopping me).
The best way to talk to a 9 is to be constantly present, alert, responsive, etc, but not aggressively so- just calmly so. Personally I LOVE when people ask me questions- it really flatters me that they want to hear what I have to say. But yeah don't ask TOO many I guess... try to judge by their body language if they like your questions or not.
People always say that to be a good listener, just shut up and pay attention... Personally I find that if I'm talking about myself and the other person is just being totally quiet, I get really uneasy, because they seem bored and they're not validated what I say. The best people to talk to let me talk for as long as I want, but they also do things every now and then to let me know that they're listening and that they care, i.e. nodding, saying "uh huh", "I know what you mean" etc, occasionally putting in comment or anecdote from their own life (but not taking over the conversation of course).
And while we're on the topic, I'll mention that the very WORST kind of person to talk to for a 9 (or maybe for anyone...) is someone who talks continually in a monologue so you have to fight to get a word in edgewise- and sometimes they change the subject without giving you a chance to make a comment about something on the last subject.
As a 9 I always thought I just had to wait for a natural place in the conversation for me to say something- I'm only just learned that I CAN actually stop them and say "wait let me say something before you change the subject" - I CAN actually just speak over them if I need to.
My absolute worst pet peeve has been when I'm telling a story or discussing something and I'm only in the middle of it, but someone jumps right in and goes "OH YEAH I know what you mean!!" and just takes it away, and thats the end of my story. It only occurred to me recently that I can actually say "wait, let me finish." (I try to use my tone of voice to make it sound casual and not rude.)
I've learned to sometimes just wave my hand around or something funny when I want to speak, because it actually gets peoples' attention. (I realize this has turned into advice FOR 9's and not talking to 9's, but maybe it would help you to know what our issues are.)