The Access Board produced 5 handouts on classroom acoustics for parents; you can see them online at http://www.quietclassrooms.org/ada/ada.htm. There are also printed copies available in Spanish.
Workplace accommodations under title 1 (and 2) can include assistive listening systems. See more detail at http://www.access-board.gov/adaag/about/bulletins/als-index.htm and http://www.access-board.gov/research/interference.htm. Assembly areas that provide amplification are required to install ALS.
The Access Board is also working on referencing S12.60-2002 in the International Building Code. This would provide for much-needed local enforcement and would facilitate (via harmonization) inclusion in the ADA Accessibility Guidelines (ADAAG).
– Thanks to Lois Thibault, US Access Board and NVRC, Fairfax