I saw on the news last fall about the version of "The Lion King" that was altered to be autism friendly. "The Lion King" will be playing again in September and "Mary Poppins" will be playing in April.
One of my cousins has a daughter with autism. I think this is a wonderful thing.
http://news.yahoo.com/2-more-autism-friendly-shows-planned-broadway-231102779.html
Given how prevalent autism has become I think this is great. Honestly I could do with fewer jarring sounds in my life myself. 
It sounds like the changes aren't too drastic. It doesn't really sound like you'd be "missing anything" if you went to one of these shows.
Leave it to Disney to make things more friendly for everyone! This is fantastic for all sorts of people!
Wow, great step! I think this is a fantastic idea. Our local theater has started having autism-friendly showings also.