Here is a video (below) from an American university about designing for people who are deaf or hard of hearing. It shows the importance of thinking through how deaf people need to see everything that is going on, including people they are communicating with. Once again, considering a marginalised group in designs enhances the environment for everyone.
On a related matter, Andrew Stewart from Printacall has done some great research on eligibility for the NDIS for people who have hearing loss, and produced a detailed document that answers just about any question on the matter.
For more on DeafSpace design and concepts go to the Gallaudet University website.