Both of my parents are deaf. You can obtain 2 weeks prior to your trip a schedule, detailing when and where a sign language interperter will be. There is a contact person listed on allearsnet.com where you can obtain the info.
Some of the monitors throughout the parks have closed captioning. There are also reflective captioning devices that are available for some of the shows and 3D movies. There is also a handheld device that can be worn around the neck. My parents hate it. It isn't very light and can be bothersome to carry around. They have decided not to use it.
There is reserved seating for those needing the interpreter/reflective captioning and the members in their party. This is nice so everyone can sit together. However, sometimes the location of the seating isn't the best and while watching the interpreter, they miss the show itself.
When you make your reservatios, inform them of the situation and have them make a note on the reservation that he will need to have a ttd, alarm clock, etc for the deaf. My parents have done this. Usually, upon check-in, the front desk will have someone come and set it up. It would be great if they'd do this prior to the arrival. We have visited a Holiday Inn Express where it was all set up before we got there. It can take a while for this to take place, but at least they have it available for him.
Disney is pretty good about what they offer, but it does have a long way to go. You'll have to plan your trip based on where the interpreters will be and when. My parents have enjoyed their several trips to WDW. Hope this helps out and let us know how the trip goes!
