T-Switch and Telephone by Ron Vickery
Editor: One of the email lists I read recently had a very interesting discussion on T-Coils and the telephone. Ron Vickery ( Ron.Vickery@usa.net) made some particularly interesting points, so I asked him for permission to share them with you. He graciously agreed, so here are excerpts from his comments.
1. All corded phones purchased in the US since 1989 and all cordless phones purchased after 1991 must be hearing aid compatible (HAC). (Cell phones are excluded, but they are under review.) Specialty phones, phones specifically made for HoH people, must be HAC too, but the difference is they have more output and therefore more radiation. [Ed: This radiation is a good thing, as Ron goes on to explain.] More radiation means a hearing aid with a telecoil can receive the signal better and not receive as much EMI. (EMI means Electromagnetic Interference – the hum and buzz we get from transformers, fluorescent lights, etc.). The amount of radiation specified by the HAC ought to be enough, but for some reason, people still report they cannot hear well in telecoil mode. Maybe a HAC phone is not generating as much radiation as it is supposed to, or maybe the user’s hearing aid is not sensitive enough in telecoil mode. Some specialty phones have a connector that allows a silhouette, neckloop, or assistive device to be plugged in. (I don’t know if anyone besides me calls them specialty phones.)
2. There may be some phones installed and in use before the HAC went into effect, and those phones may or may not be hearing aid compatible. However, the HAC was extended to workplace phones in 1999, and hotel phones were included in 2001.
3. HAC originally meant that the phone generates radiation at a specific minimum level. If it does, then a hearing aid in telecoil mode with a certain sensitivity ought to be able to receive the signal. Volume control was added to the HAC specification in 2000.
I use the telecoil almost exclusively – on the phone and everywhere else. I hardly ever use the microphones on my hearing aids. I hardly ever use DAI mode. The telecoil is just perfect for me and I use a neckloop for everything. My hearing aids are 5 year old, (maybe 6 or 7 years old) analog, high power Oticons. (E39PL) It is virtually impossible for me to hear on a phone without using the telecoil, but when using it, I can make the sound just as loud as it needs to be.
For me, the big problem on the phone is long distance. Local calls are no problem at all, when using my phone equipment. The difference with long distance is that it is NOT “As clear as a bell”, as some long distance carriers claim. Sprint claims “You can hear a pin drop.” I have found on long distance the signal level is low, distortion is high, and line noise is high. There are no hearing aids and no amplified phones that will correct those problems. If they are corrected, the long distance carrier has to do it.
However, I have found that long distance on digital cell phones is much, much better. I have just started using a LG-TM510 cell phone on the Verizon Wireless service and I can talk long distance on it. What’s the difference? It’s digital! My voice and my party’s voice is broken into little bitty pieces and sent over the network as 1’s and 0’s. No chance for line noise to squeeze in between the 1’s and 0’s. The phone is HAC and there is little interference resulting in its communication with the cell tower. (The interference gets worse as you move into a fringe area, but with luck you will move into another cell tower range before that happens.)
It would be nice if hearing aid manufacturers could design a telecoil that was equally sensitive in all directions… an “omni”. On the other hand, an omni may be worse about picking up stray EMI, and a directional telecoil may be better, like directional microphones.
So, how about two telecoils, one oriented horizontally and the other oriented vertically, with a switch to select which one you wanted to use?
A room-sized audioloop that lays on the floor has a vertical orientation. Therefore a telecoil in a hearing aid with a vertical orientation would be best. It doesn’t matter much if you picked the audioloop up and fastened it to the walls, or the ceiling. It still has a vertical orientation and the telecoil would receive the same signal level if the distances involved were the same and there were no barriers to the propagation of the signal. The signal can come from below the telecoil (loop laying on the floor) or from above the telecoil (loop attached to the ceiling).
The axis of a telephone handset coil is mostly orientated horizontally, depending on how one holds the handset. So it would appear that a telecoil installed horizontally would be best. Likewise a silhouette coil axis is horizontal. It’s hard to say about a neckloop – what the axis is. It seems mostly horizontal to me, but at right angles to the axis of a silhouette. Problems, problems.
Well, a silhouette is so close to the telecoil and most devices a silhouette plugs into can deliver a lot of power, so orientation is probably not an issue for silhouettes. Telephones do seem to be an issue because their power is much less.
Neckloops seem to be an issue for a lot of people, but not me. I blast so much power into a neckloop that I can hear it when it is hanging on the wall, and other people have told me they can hear my neckloop when it is around *my* neck and not theirs. (That makes it nice to cozy up to your favorite squeeze.)
I have never seen any published specs on the pickup pattern – area of sensitivity – for telecoils. It would be nice if we knew that when we were considering purchase.