Using T-Coils (Telecoils) to Couple Your Hearing Aids to Various Audio Devices

© December 2005 by Neil Bauman, Ph.D.

Question: I'm a bit confused about how to use the t-coils in my hearing aids with various assistive listening devices and other audio devices. What do I need to do? What do I need to get?—C. J.

Answer: I'm glad you want to use your t-coils. You'll find that your t-coils are wonderful inventions. With them, you'll hear better in many difficult listening situations. I know I do.

As their name implies, t-coils are simply tiny coils of wire mounted inside your hearing aids. In addition to the name t-coils, you may hear people refer to them variously as telephone coils, tele-coils, audio coils or t-switch. These terms all mean the same thing.

The big advantage of using your t-coils is that they generally cut out background noise so you only hear the sounds from the device you are listening to. You will hear loud, clear sound with little or no interfering racket. This is because by switching your hearing aids into their t-coil mode, you typically automatically turn off your hearing aids' microphones. Thus, the only signal you hear is from the device you are plugged into.

You'll be able to use your t-coils more effectively if you understand a bit about how they work. Here is a very simple physics lesson on the principles behind your t-coils.

Alternating current and pulsing direct current (such as you would find in the output of any audio device) produces a fluctuating magnetic field as it flows through any wire. This magnetic field extends out some distance from the wire. It may be only an inch or two, or as much as 20 feet or more—depending on the amount of power flowing through the wire and whether the wire is straight or coiled, and if coiled, how many turns of wire there are in the coil.

This fluctuating magnetic field will induce an identical electrical current in any wire (or coil of wire such as a t-coil) that lies inside this magnetic field. Thus, if you have the t-coils in your hearing aids turned on, any nearby fluctuating magnetic field will induce an identical signal into your t-coils, which your hearing aids then amplify. You hear this as sound.

Note: since house current alternates at 60 cycles per second, the wiring in your house (or any other building) can cause annoying interference if you are close to it. This interference typically sounds like a loud buzz. Some florescent light fixtures, CRT computer monitors and televisions can all cause interference. If this happens, you just need to move a bit away, and the interference will typically fade out.

In order to hear sounds via your t-coils, the audio device you want to use must generate a fluctuating magnetic field that is strong enough for your t-coils to receive. To make this happen, instead of using earphones or loudspeakers, you just connect a loop or coil of wire to the output of the audio device. This produces the magnetic field that your t-coils will pick up.

There are several of these loop gadgets that you can plug into the output of audio devices to generate the necessary magnetic field. They include such things as room loops, neckloops, silhouettes and ear links.

From the perspective of a t-coil user, the room loop is the simplest to use as you do not have to do anything other than switch your hearing aids to their t-coil mode. You will then (hopefully) hear beautiful, clear sound in your ears. The people running the audio system have already looked after the device that produces the magnetic signal your t-coils pick up. (In case you are interested, it is basically a loop of wire that runs around the perimeter of the room. This wire is then plugged into a loop amplifier.)

You will find room loops used in a few churches and other public buildings. These are becoming more and more common as the word gets out. For a listing of some of these looped buildings in the USA, go to http://www.puredirectsound.com/id19.html.

If you wanted to, you could purchase a small loop amplifier, run a loop of wire around a room in your house and listen, for example, to your TV as long as you are inside the loop. I looped half of my house with one such amplifier. Thus I can clearly hear my TV from any place in that half of the house—both upstairs or downstairs! If you are interested in a room loop of your own, read, "Loop Systems—the Best-Kept Secret in Town!"

If all you want is a personal loop for yourself, you need to get either a neckloop, silhouette, or ear link. You then plug it into the audio output jack of whatever audio device you want to listen to. For example, you could plug one of these devices into any of the small portable assistive listening devices (ALDs) such as PockeTalkers, Sound Wizards, FM systems or Infrared systems. You could also plug them into any landline or cell phones that have the appropriate jack on them. (Some corded phones and all cordless phones have this jack on them. So do most cell phones. In addition, some phones made especially for hard of hearing people have these jacks. I have 3 such phones of my own.) In addition, you could plug them into the earphone jack of any computer, radio, TV, stereo, tape player, CD or DVD player, iPod, MP3 player, etc.

What Are Neckloops, Silhouettes & Ear Links?

Neckloops, silhouettes and ear links all do basically the same thing. They are loops or coils of wire that plug into the audio device you want to listen to and radiate a magnetic field that the t-coils in your hearing aids pick up.

Neckloops are just what they sound like—a loop of wire that hangs loosely around your neck with a cord that plugs into the device to which you are listening. (Williams Sound Neckloop shown at left.)

A silhouette looks like a behind the ear (BTE) hearing aid that got run over and squashed by a "steam roller." It is about 1/8 inch thick and contains a flat coil of wire inside it. You place the silhouette over your ear—right beside your BTE hearing aid. A wire runs from the bottom of the silhouette to the audio device of your choice. (Silhouette shown at right.)

An ear link (Music Link, T-Link, NoiZfree™ Telecoil Induction Earhook, etc.) is worn like a silhouette—but it is much smaller—about the size of a coat hanger wire so it virtually doesn't take up any space behind your ear. (In concept, think of the "hook" part of a coat hanger. Wrap a very fine wire around this hook, place this hook over your ear and voila, you have an ear link.) As with the silhouette, a wire runs from each ear link to whichever audio device you are listening to. (Music Links shown at left.)

What's the Difference Between These Devices in Real Life Situations?

Although each of these devices do the same basic job, there are good reasons why you may choose one of them over the other two. Here are some things to consider before you purchase either a neckloop, silhouette or ear link.

Two Ears or One?

If you wear two hearing aids, then you will want to get devices that will work with both hearing aids. Neckloops, by their very nature, work with two hearing aids if you wear two. Both the silhouettes and ear links come in two models—single-ear or dual-ear versions—so get the dual ear versions if you wear two hearing aids.

Mono or Stereo?

Before you buy one of these devices, decide whether hearing true stereo sound is important to you or not. (Stereo sound allows you to hear different sounds in each ear, so for example, when listening to stereo music, it seems the various instrumental sounds come from different locations.)

The output of almost all ALDs (PockeTalkers, FM systems, etc.) is mono. In contrast, the output of almost all standard audio devices (radios, computers, iPods, CD, DVD & MP3 players, etc) is stereo. If you have two hearing aids and listen to these latter devices, then you will likely want stereo capability.

Neckloops are mono devices. This means even if you are listening to a stereo device, you will only hear mono sound, that is, the same sound in both ears. (I call it dual mono).

In contrast to neckloops, the ear links are stereo devices, so you will hear true stereo sound if you are plugged into a stereo audio system—one channel in one ear, and the other channel in the other ear.

Silhouettes, by their nature are really stereo devices. Unfortunately, in actual practice, dual silhouettes are typically hooked together into a mono plug—so you just hear dual mono, not stereo. If dual silhouettes are wired to a stereo plug, then they are indeed stereo devices. So check whether the plug is mono or stereo, if you are considering buying silhouettes.

Note: you can easily convert stereo ear links (and stereo silhouettes, ear buds and earphones too) to work on mono devices by using an adapter. The reverse is not true. You cannot make a mono device like a neckloop into a stereo device.

If you are hooking a mono loop (neckloop or mono silhouettes) to a stereo audio system, you need to get the appropriate adaptor jack or you will only hear one channel of sound (and will short out the other channel while you are at it, which may damage the stereo system). To prevent this, get Radio Shack adapter #274-0374 ($2.99).

If you are hooking a stereo loop (ear links or stereo silhouettes) to a mono output device (e.g. PockeTalker, FM system), you need Radio Shack adapter #274-882 ($3.99). Otherwise you will only hear sound in one ear, but you will not damage the device.

Head Movement

By their very nature, t-coils are very directional. For the best signal you need to keep them in the same plane as the transmitting loop. Otherwise, the signal will drop and may almost fade out completely. This is especially true if the signal is produced by a low power (battery-operated) device.

Fading can be a real problem when using neckloops. You may be sitting watching a speaker and hear him perfectly. Then you look down to write some notes and his voice seems to fade away. This is because your t-coils are now not oriented in the same plane as they were when you were looking up.

If this is going to be a problem, then getting silhouettes or ear links will solve it. This is because they sit on your ears and always remain in the same relative position to your hearing aid t-coils no matter how you move your head. In my opinion, this is a big plus for these two devices over neckloops.

Wired or Wireless

A possible drawback to the silhouettes and ear links is that you have wires hanging down from each ear. You can catch these wires on things and inadvertently yank them off your ears. Some people just don't like having wires hanging from their ears. For others, it doesn't bother them at all.

With a neckloop, you don't have any wires going to your ears. In addition, you can actually wear it under your clothes if you want it to be completely invisible—except for the cord that attaches to the sound source.

Size Matters

If you wear glasses and BTE hearing aids, "real estate" behind your ears is at a premium. You may not have enough room for silhouettes, especially if you have smaller ears. This is where the ear links (Music Link ear hooks shown at right) really shine. They are so small that you can put them on, and your hearing aid can sit right on top of them so they virtually don't take up any real estate at all. If you have really tiny ears, a neckloop may be the answer for you.

T-coil Orientation

T-coils can be mounted in your hearing aids in one of three basic orientations—horizontal, vertical and diagonal. Horizontal works best for vertically-oriented loops. Vertical t-coils work with horizontally-oriented loops. Diagonally-mounted t-coils are a compromise. They neither work really well with vertical loops nor with horizontal loops, but generally produce an acceptable signal for both orientations if the signal is strong enough.

Thus, depending on the orientation of your t-coils, you may find that the signal from a neckloop is not very good for you, or it may be excellent. You have to try one out to see how it will work in your particular case.

T-coil orientation is not as much of a problem when using either silhouettes or ear links because these devices are so close to your t-coils that even when their orientation is mismatched, they generally still produce an adequate signal.

Signal Loudness

How well you hear in t-coil mode can really vary. It may depend on the power of your hearing aids, how "good" your t-coils are, the orientation of your t-coils inside your hearing aids and the strength of the output signal you are listening to.

If you have trouble hearing the signal through your t-coils, then you need the signal source closer to your hearing aids. I have seen some people with neckloops drape their neckloops over their ears so they can hear. This looks "funny," but it works. If this is your situation, a much more elegant solution is to get silhouettes or ear links. This way, these devices are very close to your hearing aids so transfer a much stronger signal.

Small battery-powered ALDs may not have the power to adequately drive a neck loop, but they have plenty of power to drive ear links and silhouettes. If this is your case, then don't bother with neckloops.

Tip: If your t-coils do not produce a loud enough signal, take your hearing aids back to wherever you got them and have your audiologist adjust the t-coil output to be louder. Unfortunately, t-coils often are not set up properly when you initially get your hearing aids.

Mechanical Considerations

Some silhouettes have cords that plug in to them. With time, the plugs can get loose or break. With other silhouette-type devices, the wire often breaks. With the ear links, there is no plug to get loose so this may be a better option.

Look for a device that has at least a year's warranty. If the manufacturer only warranties their products for 30 to 90 days, you may well be throwing good money after bad. Why buy a product that may break the day after the warranty expires?

My Personal Choice

I like my Williams neckloop ($39.70). It has served me well for several years. However, when I received some sample ear links (Music Link, T-Link), I immediately fell in love with them. They work so well-beautiful strong signal, take up so little space on my ears and cost less than the other devices.

The ear links come it two versions. Use the dual "Music-Link" ($49.00) to listen to all the various audio devices mentioned earlier, except cell phones. It has a standard 1/8 inch (3.5 mm) stereo plug on the end that fits most audio devices.

The dual "T-link" ($59.00) is actually a hands-free cell-phone headset. It includes a microphone built into the cord and terminates with a standard 3/32 inch (2.5 mm) stereo plug that fits almost all modern cell phones.

I wanted to see how well the T-link works, so I borrowed my wife's cell phone (which I can't hear on), plugged in the T-link, put my HAs into t-coil mode, and phoned the importer of these wonderful devices. I talked to him for an hour. Beautiful clear sound! No interference from the cell phone. I think you'll be as impressed with them as I was.

To learn more about the ear links or to purchase them, click on either Music Link or T-Link.
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There you have it. The pros and cons of neckloops, silhouettes and ear links. For myself, my first choice is the ear links, followed by the neckloop, with the silhouette bringing up the rear (because of physical and mechanical constraints such as uses up too much "real estate" behind your ears, cords prone to break, plugs come lose, higher price—$68.00 to $199.00). You may come to a different decision. That is perfectly ok. The main thing is that you use your t-coils to help you hear better whenever you encounter difficult listening situations now that you know how.