Few people are aware that the orientation of the telecoils in their hearing aids is important. Normally, a person just buys telecoil-equipped hearing aids and never gives a thought as to how the telecoils themselves are physically oriented in their hearing aids.
Orientation is important because maximum coupling (meaning the loudest signal) occurs between two coils (for example, between a telecoil and a room loop) when both coils are oriented in the same plane as each other. Thus telecoils must be oriented in the same plane as the transmitting loop for maximum signal strength.
A room loop is a flat coil of wire laying horizontally. (Think of a doughnut laying flat.) Thus, for maximum signal, the coils in your telecoil should also be horizontal.
Since a telecoil is wound on a thin tube (think of a stack of doughnuts piled 6 or 8 high), the telecoil must be mounted with the tube vertical (so the coils of wire themselves lay horizontally). Thus, when a telecoil is physically vertical, its coils are in the horizontal plane exactly the same as a room loop.
Passive Tibbetts telecoils
Photo courtesy www.tibbettsindustries.com
If the telecoil is mounted horizontally, the coils of wire are oriented vertically (think of a stack of doughnuts tipped over so each doughnut is standing on its end) and will best pick up a signal device mounted vertically (i.e. the coil in a phone handset).
Therefore, a horizontally-mounted telecoil works best when using the phone while a vertically-mounted telecoil works best when using a room loop or neckloop.
Often hearing aid manufacturers compromise and set the telecoils at an angle so they will work both with the phone and with room loops—but this is done at the expense of optimum volume in either plane. That is why when you tip your head, the signal may fade out or get louder. If your telecoils are mounted diagonally, tipping your head 45 degrees one way will give a stronger signal from a room loop and tipping your head 45 degrees the other way will give a stronger phone signal.
Strength of Telecoils
Often the signal picked up by the telecoil is not as strong (loud) as a signal picked up by the hearing aid’s microphone. Therefore, when switching over to your telecoils, you may also have to turn the volume on your hearing aids way up.
If this is the case, you really need amplified telecoils (rather than the passive style shown above) so the output of the telecoil closely matches the output from the microphone. Tibbetts Industries make a great little amplified telecoil.
Digital hearing aids typically have telecoils that can be programmed to any given volume. Therefore, make sure you ask your audiologist to program the volume of your telecoils to your satisfaction.