We have seen Wishes and Illuminations at Disney and they both had music playing during the fireworks show so that does help a little with the "boom" noise but it doesnt eliminate it.
Not too long ago there was a thread with some suggestions on how to handle the noise factor for children who are very sensitive to it. My DS is now 11 and he still is uncomfortable with very loud noise although he is much better than he was.
What worked for us at Disney was bringing along his portable cd player and his favorite music cd. We had a boat cruise booked with our whole family and we really wanted all of us to enjoy the show together but we didn't want him to be upset or forced into it in any way. He liked the show - it was just the noise that bothered him so right before the fireworks started he put on his headset and listened to music and watched right along with us. It worked out great and his cd player was small enough to keep in our backpack anytime we needed it, plus we used it on the plane ride.
Good luck and enjoy your trip.
