The Americans for Disabilities Act General Guidelines (2010, PDF)
require that "an assistive listening system shall be provided" in assembly areas that have audio amplification. One in four assistive listening receivers must be "hearing-aid compatible"---but this requirement is waived for facilities "served by an induction loop."
In many settings, hearing aids are insufficient,
because turning up their volume magnifies extraneous noise and
reverberation as well as the desired "signal." Assistive
listening systems clarify sound by eliminating the negative
effects of distance, noise, and reverberation.
|Lecture hall and seminar room, Royal
Society of Edinburgh
Ideally, people with hearing loss would receive this broadcast
sound directly through their own inconspicuous and personalized
hearing aids. If public venues would install loop systems,
more and more people in the USA, as in Europe, would become
equipped to use the system. In the interim, loop systems can
serve those not equipped with hearing aids just as do infrared
and FM assistive listening systems--with portable receivers
and headsets. (Rarely, however, are existing portable receivers checked out and used; most people are either unaware of their availability, unwilling to fuss with the hassle, or averse to being conspicuous.) Over time there would be less and
less need to purchase and maintain portable receivers as more and more people harness the power of the
optimum assistive listening system.
For theaters, this means payback from increased attendance
at movies and plays by people with hearing loss (many of whom
report no longer going, because of the challenges of hearing).
For courts, this means jurors who understand essential proceedings
(and who can also be assisted in understanding jurors during
deliberations). For auditoriums this means making one's events
optimally accessible to all attendees.