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Hearing Loops and Induction Loop Technology
What is a Hearing Loop?
A
Hearing Loop uses Induction Loop Technology to transmit sounds directly to a hearing aid's
built-in wireless T-coil receiver.
What's the benefit to
hearing aid users?
Hearing Loops provide improved listening
clarity for people with hearing loss who experience difficulty and fatigue, when
trying to understand speech, because of distance, reverberation, and distracting background
noise.
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Reduced distracting background noise
(when using T-coil only program)
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Reduced reverberation and sound distortion
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Reduced listening fatigue
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Improved
listening clarity and understanding
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Improved hearing at a distance from the speaker
Why not use FM?
The greatest difference between Induction Loops and other assistive listening
technologies is that users do not need to be given a receiver; they already have one!
As long as the hearing aid
or cochlear implant (CI) has a built-in
T-coil (telecoil), that's all users need. There is no extra expense or need
to supply each user with a loaned, system compatible receiver. That means that when public facilities like meeting halls, theatres,
churches, post offices, hotels or banks are looped, all a user has to do is switch
their hearing aid or CI to the T-coil program. Now they can experience the
improved clarity, easier listening, and better understanding that Hearing Loops
provide. Once the Induction Loop system is in place, any hearing impaired person
who uses a T-coil program can benefit from it; there is no user limit.
What are
the advantages of Induction Loop Hearing Systems?
Induction loops offer low maintenance, easy to use, "set-it and forget-it"
technology.
From a business perspective
Businesses do not have to purchase,
maintain, recharge, repair, replace, sanitize, or issue and retrieve
multiple assistive listen device receivers: users utilize the built-in
T-coil wireless receiver of their T-coil enabled hearing aid or cochlear
implant.
An audio frequency induction loop system is flexible in its ability to
easily accommodate one or a thousand users; there is no limit to how many
may utilize the system. Conversely, large-area assistive listening
systems, that require each user to have a personal receiver, will have a
finite user capacity that is dependent on: projections of how many people
might wish to utilize the system; how many receiver units were budgeted
for and purchased; how many receiver units are currently charged,
maintained and available for loan.
Also, user acceptance and utilization levels are likely to be much
greater than with other assistive listening technologies. These other
technologies come with the inherent negative stigma of having to wear a
device or headset that advertises the user's disability and raises
concerns about the maintenance and hygiene of borrowed equipment.
Hearing loops are an appropriate assistive listening solution for both
short-term (transient) and long-term (non-transient) listening
environments.
Hearing Loops offer a cost-effective, large-area assistive listening
solution with the likelihood of a high degree of user acceptance and
utilization as well as considerable ongoing savings in equipment
management and personnel training costs.
From a user perspective
Users can take advantage of their personal hearing aid’s built-in
T-coil wireless receiver without having to rely on borrowed equipment from
facilities that may not maintain it correctly.
Also, hearing aid users are able to benefit from hearing loop technology
while still enjoying the customized hearing correction that their hearing
aids provide. This is not the case with ear bud and stethoscope style
assistive listening devices that require the user to remove their hearing
aids!
There’s no standing in line to checkout assistive listening devices and
return them after use. And, concerns about hygiene and sanitization are
eliminated.
Induction Loop technology uses a universal frequency
A hearing aid user's T-coil will work in any looped facility. This is not
the case with FM and Infrared technology, where transmission frequencies
may vary from one facility to another and require that the user has, or is
loaned, a compatible receiver.
Induction Loop technology is an International standard
For example, a T-coil user from the United States would have no problem
using their hearing aid's T-coil in Amsterdam airport. Unfortunately this
is not the case with other technologies such as FM and Infrared where
transmission frequencies vary from one country to another.
What is a T-coil or telecoil?
"T-coil", "telecoil", "T" program
or even "telephone coil" are all equivalent terms
used to describe the induction loop wireless receiver.
The induction loop receiver is housed
inside a hearing aid or CI (cochlear implant). The receiver picks up the electromagnetic
field from a telephone handset or induction loop system, which is then converted
into analog sound.
The
T-coil or telecoil is only activated when the, hearing aid or CI, "T" program is
selected by the user. Selecting the "T" program automatically disables the
hearing aid or CI
microphone. This is beneficial because it eliminates "feedback whistling" and
reduces distracting background noise.
Some hearing aids have an optional "T+M"
program where the T-coil ("T") and microphone ("M") are active simultaneously; this
may somewhat negate the
benefit of reducing background noise. Another option for hearing impaired users
with two hearing aids is to switch one aid to the "T" program, leaving the other
to pick-up environmental sounds.
Some newer digital aids offer 'automatic'
program selection (as opposed to manual switching). The aid attempts to identify
the sound environment and automatically select the most appropriate program. Whether this is successful or not, will depend on the
design of the aid and the perceived strength of the induction loop field from
the telephone handset or induction loop system.
How
does using Induction Loop technology reduce background noise?
When the T-coil (telecoil) program is selected, the hearing
aid’s external microphone is automatically disabled. This eliminates
"feedback" and reduces distracting background noise providing the listener with
a
clearer signal from
the sound source. This is referred to as, improving the ‘speech to noise ratio’
(SpNR) or 'signal to noise ratio' (SNR) and is a very beneficial strategy for improving speech comprehension.
How do
Induction or Hearing Loops work?
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A Hearing Loop (transmitter) creates
an electromagnetic field that is picked up by the T-coil (receiver) in
a hearing aid and
converted to audible sound. The electromagnetic field actually "induces"
an equivalent current in the T-coil, hence the the term Induction Loop.
Induction Loop is a more correct term, but Hearing Loop does a better job of
describing the purpose and benefit.
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Physically, a
Hearing Loop is
simply a
loop of copper wire or flat copper tape (for installation under carpeting).
Hearing
Loops can be very large, encircling the perimeter of a meeting room,
theatre or church.
Hearing
Loops can also be quite small, embedded in a chair
cushion loop-pad or quite simply a loop around your neck - a neck loop.
Hearing
Loops may not even look like a loop!
For example,
T-Link and
Music-Link
don't look like Induction Loops, but internally they each have a complete loop
of wire. Neck loops and ear hooks are sometimes called "couplers" because they
provide the inductive coupling (link) to the T-coil receiver.
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Electronic audio input from a microphone, TV, audio player,
telephone or any sound system feeds into a driver (amplifier).
The Hearing Loop driver conditions the
low-level, audio frequency electric current before it enters the wire loop, ensuring that the
resultant electromagnetic field is consistent and at the correct
strength. This is the same type of low-level, audio frequency electric current that
feeds into the loud speaker wires of a regular audio system.
Technically speaking, an Induction Loop or Hearing Loop is referred to as an Audio
Frequency Induction Loop System (AFILS).
AFILS drivers come in different sizes depending on the area of the Hearing Loop.
UniVox
DLS-50
is an example of a small-area driver intended for home use or areas up to 400
sq. ft. More powerful drivers available from TecEar cover
areas up to 7,000 sq. ft.
Personal Hearing Loop devices, such as the
T-Link and
Music-Link that use inductive ear hooks or neck loops, don't require a separate
driver. Instead, they draw their audio
current directly from the device (e.g. iPod or cell phone), just like
regular headphones and headsets.
Is there an installation
standard to ensure the consistent quality of Hearing Loops?
Yes, it is important that purchased AFILS equipment and the installed wire loop
design produce a uniform induction field that provides the correct strength and
frequency response.
Induction loop systems are used worldwide and are required to meet an
established international standard, which was developed under the auspices of
the IEC (International Electrotechnical Commission).
The International number of this standard is IEC 60118-4. This is also
variously known as EN60118-4 (in Europe), or by specific national publication
numbers in other parts of the world.
This standard defines the strength of the magnetic field, frequency response
and methods of measuring these requirements. It also gives a maximum level for
interfering signals.
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Compliance with the standard will be the result of correct
equipment specification, wiring loop design and installation. All
installations should be tested with a Field Strength Meter to verify
compliance.
Where
are Hearing Loops and T-coil inductive accessories used?
Almost anywhere!
Hearing Loops come in a variety of
styles and sizes. And, depending on their size and type, may be permanent or
portable.
Large public facilities like churches, concert halls and
meeting rooms are ideal places for Audio Frequency Induction Loop Systems -
Hearing Loops.
Service counters at post offices, banks and hotel
reception desks can use Hearing Loop devices such as the
Soundshuttle.
Doctors, health workers, teachers and other
professionals who have hearing loss or who need to interview people with
hearing loss can use the portable
Clipboard Loop.
Hard of hearing people can easily install their own home
Hearing Loop for TV and entertainment center listening using a
Home Room Loop Kit. The wire loop is laid under carpet,
behind baseboard molding, a picture rail, or even in a basement ceiling.
A very easy and quick installation is the
Chair Loop Pad Kit. A factory made loop pad
is placed underneath the cushion of a favorite chair for easy and
enjoyable TV and audio listening.
Pocketalker, iPod and other MP3 player users can simply plug in the
Music-Link.
Music-Link provides a stronger signal than most less powerful neck loops.
Any corded, cordless or cell phone with a 2.5 mm headset
jack can be connected to the T-Link with its built-in microphone for clearer
hands free phone conversations.
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See the TecEar
T-coil Solutions
Guide for further selection information.
Why are Induction Loops the
best solution for "transient" listening environments?
"Transient" or short-term listening environments such as subway ticket offices, hotel check-in
desks, bank teller windows etc., are listening environments where it would be
impractical to issue assistive listening devices. Consequentially, in these types of
listening environments, FM radio and infrared technologies are of little use. On
the other hand, leveraging the wireless, T-coil receiver already built-in to a hearing
aid or CI makes perfect sense. Looping such short-term listening environments is
a practical and cost effective solution that enables hard of hearing people to
hear clearly and understand important information via their T-coil.
Of course, Audio Frequency Induction Loop Systems also offer a great,
cost-effective solution for "non-transient" listening environments too; places
where people live, work or stay for longer periods such as meeting rooms,
lecture theatres, concert halls and churches.
Can non-Hearing Impaired
people use Induction Loop Systems?
Yes, telecoil receivers are available for non-hearing impaired users who will
hear the sound via ear buds or headphones. Non-hearing impaired users will share
all the benefits of reduced background noise, reverberation, sound distortion
and listening fatigue plus improved clarity and ease of listening at a distance.
Are there Induction Hearing Loops for personal use?
Yes,
personal assistive listening devices (ALDs),
utilizing Induction Loop technology, available from TecEar include:
Music-Link allows you to enjoy music and other audio from
an iPod, MP3 Player, Pocketalker or FM assistive listening device.
T-Link reduces
background noise and makes phone communication possible with phones
that are not otherwise hard of hearing friendly. You’ll appreciate the
improved listening clarity.
The
Chair Loop Pad Kit is a great solution that enables you
to enjoy and hear TV again without turning up the volume and disturbing
others.
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See the TecEar
T-coil Solutions
Guide for further selection information.
Do other
assistive listening technologies utilize T-coil?
Surprisingly, the answer to this is yes! This is because there are very
few viable ways to introduce an electronic sound into a hearing aid.
An older option (that is rarely utilized today) is to use direct audio input
(DAI) cables that connect to electrodes on the base of a behind the ear (BTE)
hearing aid. Obviously, this would not be possible with other styles of hearing
aid that are positioned in the ear canal. Not all BTE hearing aids have DAI.
Another issue is the inconvenience of trailing wires which can get caught and
easily damaged.
Another option, which has been extensively developed by Phonak, is to attach an FM
radio receiver to the base of a BTE hearing aid via an adapter called a "boot"
or "shoe". The shoe connects to the three pins of the DAI connector and provides
the correct interface for the additional FM receiver module. These extra
components have the disadvantage of adding size, cost and electric current drain
to the hearing aid and again are not available for other styles of hearing aid.
FM receivers are designed to operate on specific FM frequencies, so
compatibility can be an issue. Commonly, FM receivers that are integrated into
hearing aids provide good individual or classroom assistive listening solutions
but are not practical for general use in public areas.
A
much newer technology is Bluetooth. Recently, an innovative Bluetooth add-on
module called "ELI" was introduced. Like the FM receivers, it attaches to
the base of a BTE aid. While an exciting technological advance, it too adds size
and cost to a BTE hearing aid and is not a practical assistive listening
technology solution for multiple users.
So, public large-area assistive listening systems (that utilize FM radio or
infrared) are left with two options: Introduce transmitted electronic sound to
hearing aids as analog sound via headphones and ear buds or use induction loop
technology and the hearing aid's T-coil wireless receiver.
The analog sound option is likely to create difficulties with feedback from
hearing aids or require users to remove their hearing aids - a rather
counterproductive solution!
That brings us
full circle back to induction loops.
Ironically, even if a facility chooses a large-area assistive listening
technology such as FM or infrared, the last few inches of the transmission (from
the issued FM or infrared receiver to the user's hearing aid) will be most
effectively
accomplished via inductive ear hooks or neck loop and the hearing aid's T-coil
wireless receiver.
When I switch to the
"T" program I hear buzzing - what's going on?
Any buzzing that you hear in the background when using the “T” program comes
from electromagnetic interference or EMI. EMI can come from electrical wiring,
fluorescent lights, TVs and CRT (cathode ray tube) computer monitors or other
electrical devices - yes, even your car!
Don’t panic!
Here are some simple tips for dealing with EMI.
1. Be a
detective!
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Turn on your
“T” program and walk around your home or office space. Buzzing if any, may
vary in strength from one location to another. Notice which areas have the
least EMI and which have the most. Try to identify the source of the EMI as
you move closer and further away from it.
2. Implement
solutions:
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EMI from wiring
or lighting may not be something you can easily control or change, but what
about relocating your desk or chair? In any case, you would be smart to be
facing people as they enter your living space so that they do not surprise
you, and you are immediately aware of their presence.
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Replacing a CRT
computer monitor with a flat-screen LCD monitor or laptop computer is a very
practical and worthwhile solution. The benefit is well worth the expense and
will even give you more desk space and bring you into the twenty-first
century!
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Another EMI
management technique is to reduce the volume level of the EMI and increase the
volume level of the sound source you wish to hear. If the background buzzing
is reduced to a lower level, you may not even notice it! Achieving this
involves two steps:
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First, reduce
the “T” program volume level so that the loudness and annoyance of the EMI
buzzing is reduced as much as possible. You can do this via the volume
control on your hearing aid or you might even consider getting your
audiologist to turn down the “T” program volume level.
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Second,
compensate for the decrease in hearing aid volume by increasing the
induction loop field strength from the sound source you wish to hear. This
can be done easily by increasing the volume setting on the induction loop
amplifier, iPod, MP3 player, computer, cell phone or telephone etc.
Now you should
be experiencing the best of both worlds: reduced buzzing from EMI and louder,
clearer audio listening from the sound source you wish to hear. I use this
technique when listening to TV via the
Chair Induction Loop Pad. The EMI in my
lower-level TV room is quite strong but I’m easily able to manage it so that I
can enjoy the amazing TV sound that comes from the
Chair Induction Loop Pad Kit.
Why haven’t I
heard more about Induction Hearing Loops?
Most Induction Loop technology available
at TecEar
comes to us from Europe. Because hearing aids with built-in T-coil (telecoil) are supplied to
hearing impaired people, via the public health services in countries like Britain and Sweden,
Induction Loop technology has taken off with many manufacturers and innovative
applications. Also, public policy mandates access for people with
disabilities, including those with hearing loss, so looped public facilities are
common.
In the United States, the situation is somewhat different. Until quite recently,
many hearing aids dispensed in the US did not include T-coils! The
technology was not widely known about or utilized. Several communities in the
States have championed Induction Loop technology in an effort to make it more
widely available, especially in public facilities. One such community is
Holland, Michigan.
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