ADA

1. Americans with Disabilites Act, ADA sets standards for accessibility for public places of assembly and other public and commercial buildings, including theatres.
From ADA History:

The Americans with Disabilities Act (ADA), signed into law by President Bush on July 26, 1990, is undeniably the most comprehensive formulation of the rights of the people with disabilities in the history of the United States or of any other nation.
More than fifty million Americans have some kind of physical, sensory, cognitive, or mental disability. Even this figure, however, may not adequately express the importance of the ADA. To appreciate its full impact, it is necessary to understand that virtually every individual and every family in the United States is touched at one time or another by the experience of disability. The ADA's far-reaching provisions for employment, state and local government, transportation, public accommodations, and telecommunications, therefore, have the potential to benefit almost everyone.

See the websites: http://www.ada.gov/cguide.htm and http://www.access-board.gov/adaag/html/adaag.htm for more information.

2. Audio Distribution Amplifier.