I'm a 17-year-old Korean male and I've recently noticed that while I am able to talk normally without a thick Asian accent, as I've been told by professors I've had in the States that I sound almost like a native English speaker, my American accent comes and goes. Sometimes I'd find myself unable to pronunce certain words and mumbling over some of them. Usually my mouth and tongue would feel stiff at the same time and I end up producing tons of saliva as I talk. While I've always had this problem, I feel like it got worse about 3 months ago when I started to mimic the way Hugh Laurie speaks on House as an attempt to sound like him. Not sure if it has anything to do with my issues but I just thought I should mention it.
Also I live with my dad who speaks very poor English. I started speaking English with him instead of Korean so I would get more used to the language. Looking back at it, however, I've realized that this could be affecting my English, as the communications between me and my dad might have caused me to unconsciously talk like him. I've been using the shadowing method for improving my accent for a long time, but I've read this study which shows that humans learn a language from interacting and communicating with others, much more so then they do from simply listening. Could this be the reason of my struggles with the accent, talking with my father? I'm quite confused as this point and I really want to hear what you guys think. Thank you.
Shadowing method has been working alright for me so far, and another thing I've doing is recording and trying to listen for my mistakes. I'm not sure how much that will work but I'll keep it up for awhile.