For me personally, the type of noise that distracts me the most is external noise. Whether that external noise is loud music, someone tapping their foot, or just a lot of talking, all of these things can lead me to lose my focus. I find it hard to focus on what is in front of me if there is a multitude of things happening around me. To get myself back on track, I force myself to start listening intently on the speaker and then I will begin to gather back my focus. If I concentrate really hard on what is in front of me then I can slowly block out all of the external noises around me.
I agree that external noise can be overwhelming. There are times that I focus on so much that is happening around me that I lose focus on the reader. I also try to intently listen to the speaker to get back on track.