I'm 25 years old, and i am on the spectrum..i have PDD-NOS> I guess you could say i'm high functioning. I hate sudden loud noise.. earplugs make all the difference in enjoying the noiser shows. It's not so much the volume, just the suddenness of the noise that is unnerving. Before i thought of bringing earplugs, id hold my hands to my ears during loud shows..that's very conspicous and uncomfortable too.. earplugs solve both worries. I am a veteran of disney parks by now.. ive been there at least 7 times.. and pretty much know where i need them. It may be useful for parents to know where an autie uses his earplugs..so here we go:
By Park:
Magic Kingdom.. just entering the park..with the steam locomotive usually just under the main gate spouting the occsional Toot just for the heck of it..
Anywhere in the park thats near a station for the railrorad. Specifically, Frontierland, Main Street USA Mickey's toon town fair.
Oh, a sweet tip for parents who want to ride the rail road: I don't mind riding the train, as long as we sit near the far back of the train. I find the whislte tolerable there.
Liberty Square: Area near the riverboat..i dont even ride the riverboat..never set foot on it.. way beyond my comfort zone. may want to earplug while in line for the Haunted Mansion.
Attraction specific:
Tomorrowland: The time keeper, stitch's great escape.
Fantasyland: Mickey's PhilarMagic
That's it for the Magic Kingdom
Epcot:
Mission Space, Test Track, Universe of Energy
Honey, I Shrunk The Audience
Nothing that i can think of in the World Showcase
MGM Studios: This one is the "Big Kahuna." I use my earplugs a LOT in this park.
Indiana Jones Epic Stunt Spectacluar: Not just while seeing the show, even being NEAR the ampitheater while a show is going on without earplugs has me scrambling for cover. (But only while out doors)
Lights, motors action extreme stunt show
Muppet Vision 3D
Studio Backlot Tour
Fantasmic!
Animal Kingdom:
It's Tough to Be a Bug
Dinosaur!
Expedition everest(not sure on this one, havent experienced it without the plugs..was plugging just to be on the safe side)
These are attractions that ive experienced. Some of the attractions i havent been to, so i don't know how startiling they are. Hope this is helpful to someone!
And, you mileage may vary..i don't mind volume so much as loud sudden volume.. your experience may be very different.