Both internal and external noise distract me, but I'd say that external noise often distracts me more than internal noise does.
For starters, when we were watching the Ted Talk today in class, the speaker made a lot of smacking noises with her mouth. This sound is disgusting and was nearly the only thing I could focus on for the first ten minutes of the video. As the video went on, I did my best to repeat her words to myself so that I had something else to think about.
Another example of external noise that really tends to distract me is when people bounce their legs in class, especially when upstairs. The rustling of pants that accompany the leg bouncing is very distracting, and when someone is doing it upstairs, the whole room shakes. The strategy I use to help me regain focus is to ask the person a question or tell them something random. This usually stops them from bouncing for a split second and then I can lock in enough in that moment that it doesn't bother me as much when it happens again later.
Internal noise really is only bad for me when I'm tired, but it definitely still hinders my focus. In summary, both internal and external noise distract me, but external noise, like lip smacking or leg bouncing, tend to distract me the most.