Telecoils and Wireless Assistive Listening
David G. Myers, Ph.D.
Imagine a future in which hearing aids had doubled usefulness. While they would serve as sophisticated microphone amplifiers (today’s common use), they would also serve as customized in-the-ear speakers for the wireless broadcast of television, PA system, and telephone sound.
Although that second possibility may sound like a futurist’s dream, it actually describes the present world in which I live.
My office phone can broadcast “binaural” sound (to both my ears), even if I set it on my desk while taking phone messages.
When I watch the TV nightly news, my TV speakers will broadcast normally for anyone else in the room. Although that sound is too faint and foggy for me to hear clearly, it’s not a problem. At the touch of a button my hearing aids become the TV speakers, broadcasting crystal clear sound customized just for my ears.
When I worship at my church (or at nearly any one of my community’s main churches) I need only press that same button and the clergy voice will be broadcast privately by my hearing aids, which receive wireless sound signals rather like my laptop receiving wi-fi signals.
Although most American readers of this book will have no clue what technology enables this doubled functionality for hearing aids, hearing aid wearers in Britain would immediately know what I'm talking about (as would most such people in Scandinavia, and many in Australia). The simple technology has two parts. The first is the tiny and very inexpensive telecoil (or t-coil) that now comes with most new U.S. hearing aids. These little coils of copper detect magnetic signals transmitted by telephones.
Telecoils and Telephones
Unbeknown to most people, telephone handsets transmit not only sound, but also a magnetic signal. By federal mandate, all wired, landline telephones manufactured in the United States since 1989 are “hearing aid compatible,” as are some cell phones. That means they transmit an interference-free magnetic signal to telecoil-equipped hearing aids. The hearing aid wearer simply activates the telecoil by pushing a button (on a remote device or on the hearing aid). Suddenly, the hearing aid becomes an ear plug, receiving no room sound. Instead it receives and broadcasts a strengthened phone signal. For this reason alone, more and more hearing aids of all sizes and cost levels are now coming with telecoils. Figure 11-1 shows how small telecoils are.
Enhanced phone listening was reason enough back in the late 1990s for my audiologist and hearing aid manufacturer to include telecoils in my hearing aids (for no additional charge). “I would strongly recommend that just about every hearing aid include one,” says the influential audiology researcher-writer and American Academy of Audiology Career Award winner, Mark Ross. “It is the position of [the Hearing Loss Association of America] that telecoils be given the prominence they deserve as a valuable hearing aid feature that will allow the expanded use of assistive listening devices,” concurs the Hearing Loss Association of America (HLAA). In Britain, where virtually all hearing aids distributed by the National Health Service come with telecoils, the assistive listening use of telecoils is well understood and, as I have witnessed during my annual sojourns there, widely applied.