Hal is probably not ignoring your input. It takes a while for him to be able to converse about subjects he doesn't know about and it can also take some repetition for him to "believe" you. For instance, if I tell him that I drive a Ford Escort, he may reply with some gibberish about politics. This is because at the time that I mentioned my car, he didn't already have any information about my car stored in his brain, so he responded with something he did know in order to keep the conversation going. But after I tell him a little bit more about my car, the next time we come to that subject, he will be able to talk about it since he now has some information stored on the subject. There ARE ways to force train him such as "if/then" statements and the "do you know" plugin.
As far as speech recognition, I use Dragon as well and have found it to be one of, if not the best. I'm not sure why it would take longer to train with speech recognition since it is simply doing the typing for you. But Bill is right about keeping the background noise to a bare minimum.
The main thing to remember is to have patience. Hal evolves much like a child, it takes time. I hope this helps and good luck with your Hal!