My coworker always jumps in my conversations?!?

I have a coworker who everytime Im having a conversation with someone, not only does he interrupt, but he TAKES OVER the convo. Even when the person deliberately says my name to talk to me. Or when I'm talkin to someone he still jumps in. For example, I asked my Asian coworker who doesnt talk alot about wearing a uniform, and before he could answer, this guy jumped in and tried to answer it for him. I SPECIFICALLY said this guys name. I really feel he is jealous of me and my relationship with others on the job. What other reason does he have for doing this??