Dear Editor:
In her recent letter, Jo Waldron of Phoenix Management misrepresents and simplifies my position on wireless add-on devices by taking a polite corridor discussion out of context.
I did try the HATIS at the EMI wireless working group meeting in Oklahoma, and I did say that I was intrigued with the microphone located on the wire cord, and that I could hear a telephone answering machine while using it. And yes, I thought the concept had promise for some people. As a Professor Emeritus of Audiology, and a hearing aid user of 45 years, I’m not about to rule out any possibility that may help some people hear better in some situations. But she should have also pointed out the qualifications I stated in the course of the same conversation: that it was necessary to systematically investigate possible RF interference picked up on the HATIS arrangement, (I don’t know what technology was used in the phone I tried) that the silhouette inductor tends to produce a great deal of acoustic distortion, and that I had tried the HATIS with my wireline phone and found that it produced no advantage over my “T” coil (and I have a severe to profound hearing loss). I also pointed out that it was still my personal belief, and the SHHH position, that all wireless phones should be hearing aid compatible-which I think [is] the crucial point.
Ms. Waldron makes other statements of questionable accuracy in her letter. She states that her hearing aid has a “153 dB” telecoil. When this has come up before, I’ve been too polite to respond, but I think it’s time now since she keeps using this number as part of her rationale for the HATIS. I would hate to think that any hearing-impaired person reading this claim in your journal, or anywhere else, would want to go out and acquire a hearing aid capable of handling 153 dB SPL output (whether the input is through a telecoil or microphone, the final product is still acoustic). First of all, I know of no commercial hearing aid with an output of 153 dB SPL, and if there were I certainly hope that there [is] no audiologist in the country that would fit such an aid. The threshold of pain is about 140 dB SPL, regardless of degree of hearing loss; at 153 dB not only will the sensation be excruciatingly painful and probably induce nausea and vomiting, but it wouldn’t take very long for sound at this level to completely wipe out any residual hearing.
I don’t know where she got the idea that “it has been proven that hearing aid compatibility only benefits those with a mild to moderate hearing loss.” As a matter of fact, it is just the opposite: most everyone with a mild hearing loss can satisfactorily acoustically couple a telephone to their hearing aid, while for those with moderate hearing losses, some can but most probably cannot. For the majority of people with moderate hearing losses or greater, a good “T” coil inductively coupled to a hearing aid compatible telephone (particularly one that provides some extra amplification) should permit them to reach the comprehension limits set by their hearing losses. The HATIS, too, requires hearing aid compatibility, that is a “T” coil must be included in the hearing aid. I should also point out that for anyone who is “totally deaf” as Ms. Waldron says she is, no acoustical signal, no matter what method of coupling, will provide an audible signal.
People with hearing losses want access to the revolutionary developments in wireless telephones now going on. We would like to pick up a phone and, within the limits set by our hearing losses, carry on a conversation with the person at the other end. This requires some kind of coupling arrangement between the telephone and hearing aid. Some hard of hearing people will be able to utilize acoustical coupling, many others can be best served with inductive coupling, while some (particularly those in the profound hearing loss category) may find an add-on device helpful. But all telephones should be accessible to all hard of hearing people, in the same way they are accessible to people with normal hearing. Just as a captioning chip is included in all new TV sets, thus reducing the cost to an insignificant level, so should all telephones include provisions for inductive coupling.
Mark Ross, Ph.D.
Professor Emeritus
University of Connecticut
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