Hearing
Instruments
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Recent
technological advances have been made which have improved
the experience of living with hearing instruments for many
hard of hearing people. The hard of hearing will always face
listening challenges, with or without hearing instruments.
Thankfully, hearing aids make those challenges easier to live
with. For thousands of people with hearing loss, amplification
has been the difference between feeling isolated and depressed,
or feeling in touch with other people.
There
is a wide range of technology available to help people cope
with hearing loss, and products grow in sophistication every
year. Varying in price, power, features, size and style, hearing
instruments are available to meet the audiological and lifestyle
demands of most clients.
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are four main categories of hearing instruments: |
Completely-in-the-canal
(CIC)
Completely-in-the-canal (CIC) are custom made so that all components
fit inside the shell, but they are worn deeper in the ear canal
than in-the-ear hearing aids (ITE's) which are described in
the following category and are almost invisible. Less amplification
is required from CIC than other types of hearing instruments
because output is delivered close to the eardrum. ClC reduces
the awareness wearers have of their own voice and their ears
do not feel as "plugged up" as with other types of instruments.
The technical term for this benefit is "reduced occlusion effect".
Wind-noise and telephones pose fewer problems to wearers of
CIC compared to the other types of instruments as well. |
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 In-the-ear
(ITE)
In-the ear hearing aids (ITE) became available in the late
1970's and are now the most popular style of hearing instrument
in North America. Consumers are attracted to the discreet
styling of ITE which come in several sizes including full
shell (large) to half shell (small). All the instruments electrical
components are housed within the custom-made shell which is
worn inserted in the ear. These devices use smaller batteries
than BTE and may have a shorter battery-life, but the microphone
is located in a more natural position on ITE than on BTE and
some people find that this provides better sound quality.
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 In-the-Canal
(ITC)
In-the-canal (ITC) hearing aids are smaller and are custom
made to fit the shape of your ear canal. These aids can be worn
during most physical activity. They also fit more deeply than
in-the-ear hearing aids and therefore are popular because of
their cosmetic appeal. All of the components within the single
plastic shell fit into the ear. |
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 Behind-the-ear
(BTE)
Behind-the ear (BTE) were the most common hearing instruments
in North America from the 1950's-1970's, and they continue
to outsell all other hearing instruments world-wide. BTE aids
are reliable and offer fitting flexibility in addition to
power. These instruments sit behind the ear and amplify incoming
sound. The amplified sound travels down a short tube connected
to a custom-fitted earmold that delivers the sound into the
ear canal, towards the eardrum.
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Not
all clients are good candidates for CIC's. People who should
not wear this type of instrument:
- produce
excess amounts of earwax
- have
extremely curvy, small or straight ear canals
- have
hearing losses of over 80 dB
- have
poor manual dexterity
- are
unable to afford a lot of money for hearing instruments
or batteries.
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| What's
Inside a Hearing Instrument? |
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All conventional
hearing instruments include a microphone, an amplifier, a
receiver (speaker) and a volume control. Tone controls and
output controls are also featured on most instruments and
the choice of circuits ranges in sophistication. Recent advances
in hearing instrument technology include digital signal processing;
multi-channel, frequency specific control of amplification;
various forms of compression which automatically ensure that
the listener does not receive too much amplification; directional
and multi-microphones, remote control and programmability.
Hearing
instruments will never completely make-up for hearing loss
and some instruments serve individual clients better than
other instruments. It is the job of hearing health professionals
to choose instruments which incorporate the style, circuit
type and additional features best suited to each individual
client; together, hearing health professionals and hard of
hearing individuals must work to find the best possible solution.
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| How
Hearing Aids Work |
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Programmable
Hearing Instruments
The advent of programmable hearing instruments has led to
new solutions to some old problems.
Single
Program devices allow the hearing professional to adjust
electronic controls in the hearing instrument using a computer.
Previously, instruments would have been returned to the manufacturer
for internal fine-tuning. People who own programmable hearing
instruments do not have to go without their devices as frequently
as those who do not have programmable instruments.
Multi-Program
devices provide the benefits of single channel instruments
in addition to having more than one "program" or setting.
This means that one program can be set for listening in quiet
environments, and another program can be set for noisy environments,
etc. The wearer is able to choose which program is best for
specific listening situations.
Digital
Signal Processing
Up until recently, hearing instruments have used analog technology
to process sound signals - most instruments still do - but
extensive research in the field of digital signal processing
(DSP) and its application in the hearing health industry is
taking place. DSP enables hearing health professionals to
sculpt the output of hearing instruments with refinement in
terms of frequency specific amplification, control of loudness
levels and working towards noise reduction. DSP is the most
promising technology on the hearing health horizon because
of the flexibility it provides to hearing impaired listeners
and hearing health professionals.
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