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Now that you have a better basic understanding of hearing,
hearing loss, and hearing
protection, let’s talk about the different types of hearing aids that are
available on the market today, should a hearing aid be recommended to help correct
a hearing loss.
There are three levels of technology available for hearing aids: analog, programmable
and digital.
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- Analog aids are the oldest technology available for hearing aids, and tend
to make all sounds louder.
- Programmable technology is being phased out, due to the advances in digital
technology and computer chips. If the hearing aid is programmable, it uses analog
technology, but ‘splits’ the sound to be amplified into two groups; one low to mid
pitch group, and one mid to high pitch group. These two groups of sounds can be
manipulated independently with the use of a computer.
- Digital technology is the latest innovation to hearing aids and works as
follows: incoming sound is converted from an analog signal to a digital signal.
This digital signal is split into a number of groups (bands), the number of bands
depending on the hearing aid manufacturer. These individual bands can be separately
adjusted by the programmer with the use of a computer. Once the manipulation of
the signal is done, the resulting signal is changed back into an analog signal which
is perceived by the user of the hearing aid.
Presently, there are three different levels of digital technology: Entry-level,
mid-level, and premium (high) level.
- Entry level: These digital hearing aids are like ‘no-frills’ products. They provide
the patient with amplification with the fewest ‘bands’ for programmer control. These
hearing aids are ideal for those patients who have only the basic hearing help needs
(Watching television, one-on-one conversation). They are also the least expensive
digital hearing aids on the market.
- Mid-level: These have a few ‘bells and whistles’. There are more ‘bands’ for programming
available and different processing strategies (ways in which the hearing aid processes
incoming sounds).
- Premium-level: The Cadillac of hearing aids. These aids are the most expensive and
have the most ‘bells and whistles’ available. Some of the features (not all of them)
include directional microphones (at least two microphones are present on the hearing
aid, which reduces [but not eliminates] background noise in back and to the side
of the hearing aid user), multiple listening ‘programs’ which allow the user more
flexibility for different listening situations, automatic feedback cancellation
(the ‘whistle’ you hear from hearing aids which can come from having a hand, hat,
telephone being placed too near the hearing aid) which detects and destroys feedback
in less than a second. These hearing aids are ideal for those patients with hearing
loss who lead active lifestyles (dining in noisy cafes, participate in meetings,
etc.) and are able to understand and manipulate the different features of the hearing
aid.
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A helpful analogy to use when thinking of hearing aid
technology is to think of the hearing aid as a home stereo system.
- An analog hearing aid is like having only a volume control on a personal stereo;
you can only make the sound louder or softer.
- A programmable hearing aid is like the same stereo system, except there are two
controls for bass and treble as well as the volume wheel.
- A digital hearing aid is like having a graphic equalizer with six different ‘slide
bars’ to control narrow ranges of sound in order to ‘tweak’ the sound exactly the
way the listener prefers it.
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Sizes and Styles
Open fit hearing aids have a plastic dome which is inserted into the
ear canal. This dome is connected to an ultra-thin plastic tube which screws into
the top of a mini-BTE which rests behind the top of the ear flap. These are the
best hearing aids for those individuals with normal low-frequency hearing that slopes
up to a moderate-severe high frequency hearing loss.
In-the-ear hearing aids are one piece, containing all of the circuitry
and controls inside a plastic shell. Of this specific type of hearing aid, there
are several sizes available:
- Full-shell: Like the name implies, the hearing aid takes up all of the remaining
room on the outside of the ear.
- Half-shell: This size has the top portion of the ‘shell’ missing.
- Canal: This fits inside the ear canal, but is large enough to accommodate a directional
microphone (see above) on the front of it..
- Completely-in-the-canal (CIC): This style of hearing aid goes completely into the
user’s ear canal and is removed with the assistance of a removal wire (similar to
the material used for fishing line) attached to the hearing aid. CICs are one of
the most appealing styles to those patients where vanity/appearance of the hearing
aid is the largest concern. A note of caution: While these hearing aids are small,
they do not allow for the use of advanced features such as directional microphones.
These aids also have a limit in terms of how much sound they can produce, and are
not appropriate for individuals with hearing losses worse than a moderately-severe
level.
Behind-the-ear is the largest type of hearing aid available, this
consists of two parts. One is the actual hearing instrument itself which hangs over
the top of the ear; the other is the ear mold, which couples the hearing aid to
the person’s ear. This type of hearing aid is generally used by the following patients:
- Children, as they are still growing, and quickly outgrow the ear mold during growth
‘spurts’ which changes the shape of the ear canal.
- Those with mixed/conductive hearing loss have pre-existing medical conditions (hole
in the eardrum, drainage from the ear, etc.) which prevent them from using a hearing
aid that is completely in the ear.
- Those with severe to profound losses need a hearing aid that must be able to provide
enough amplification without having it whistle all of the time. This is not possible
for those hearing aids that are all one piece (in-the-ear).
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