The US DoJ has put a document into the Federal Register of July 26, 2010 that describes many aspects of the cinema industry conversion to digital from film, especially as it relates to the hearing and visual impaired audience(s). The title is:
Nondiscrimination on the Basis of Disability; Movie Captioning and Video Description
On page 13 of the attached PDF (transcribed in whole from the Federal Register, with a link to the original), there are a series of 26 questions that the Department of Justice are inviting comment on. The final date for comments is: January 24, 2011.