I tell this to my MCAT Students in preparing for that, but I think it still applies---force yourself to study in a noisy place. Practice ignoring what is going on around you. Sit in a bench at the mall. Study at the book store or coffee shop. Being able to study with noise around you will help you to keep your concentration during any test when people are sniffling, shaking the table with their leg, clicking their pens obsessively, or when you are on the spot, in the hospital, needing to make the best decision possible when there is a lot of noice and chaos going on around you.
I hope that helps.