Here’s an article about T-Coil, which is becoming a key part of hearing aids.

 http://www.nytimes.com/2011/10/24/science/24loops.html?partner=rss&emc=rss

After he lost much of his hearing last year at age 57, the composer Richard Einhorn despaired of ever really enjoying a concert or musical again. Even using special headsets supplied by the Metropolitan Opera and Broadway theaters, he found himself frustrated by the sound quality, static and interference.

Then, in June, he went to the Kennedy Center in Washington, where his “Voice of Light” oratorio had once been performed with the National Symphony Orchestra, for a performance of the musical “Wicked.”
There were no special headphones. This time, the words and music were transmitted to a wireless receiver in Mr. Einhorn’s hearing aid using a technology that is just starting to make its way into public places in America: a hearing loop.
“There I was at ‘Wicked’ weeping uncontrollably — and I don’t even like musicals,” he said. “For the first time since I lost most of my hearing,  live music was perfectly clear, perfectly clean and incredibly rich.”