I personally have had trouble with loud noises and from experience I will say that what you did was clearly the best choice. By engaging the girl in the activity you are showing her that even though the event is cery loud, she can still enjoy herself and have fun. I feel that the best way to help achild like this is to slowlydesensitize them to the loud noises by engaging them in the activity which is what you were doing. You said that some of the time she didn't even have the earphones on clearly showing that she was slowly becoming accustomed to the noises at her own pace. The other teacher, by quickly engaging her in all the outside noises only caused her to feel disstressed, which will most likelt create a bad memory of the exprience and making her even morw relucetent to do anything similar. She does need to become accustomed to louder noises because things in life can be loud, especially high scool, but I think that your methoed was much more effiecient and would have a better outcome. I definately think yoy should bring this up, especially if it happens more in the future.
Sorry for any typos. I was typing quickly and I'm awful at spelling.

Things in life can have stairs too. That doesn't mean we take away someones wheel chair and try to make them walk. Whats wrong with crutches if you need them to walk,or covering your ears if you're sensitive to noise?