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What
are the 3 types of technology available in hearing aids?
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Linear:
Linear hearing aids use analog
circuitry and are the ‘most basic’ hearing aids available.
They are made at the manufacturing lab and also programmed there based
on your hearing test. They amplify
soft, average and loud sounds equally and are usually the least expensive to
purchase. |
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Analog/Programmable:
Programmable hearing aids are made at
the manufacturing lab and are digitally programmed by the Audiologist in the
office using specific software.
These hearing aids typically amplify the soft sounds and decrease the
volume of the louder sounds in the environment. Some have multiple memories for improved
understanding in various environments. |
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Digital:
Digital hearing
aids are the latest and most advanced technology available. They are also made at the manufacturing
lab and programmed by the Audiologist in the office using special
software. Digital Signal Processing
(DSP) (described below) is used in these hearing aids. These hearing aids have multiple
memories and the option of Directional Microphones (described below) to help
improve speech in noise. They can
be adjusted to automatically eliminate feedback in certain situations. They are most flexible for adjustments
and are the most expensive and advanced hearing aid technology
available. |
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Even the smallest
completely-in-the-canal hearing aids are now available in digital versions,
with as much programming sophistication. |
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What
else is special about programmable hearing aids? |
Because
of the numerous controls that are available through programming software,
hearing aid manufacturers have been able to incorporate significantly advanced
technology in programmable hearing devices. Some of these innovations are listed
below
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Multiple Programs:
Two to
four separate programs that are appropriate for different listening situations
can be loaded into the device. For instance, the user can use one program for
listening in quiet, another program for listening in a background of noise, and
a third program for speaking on the telephone. Switching from program to
program can be done by means of a remote control or with a toggle switch or
push button on the instrument. |
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Wide Dynamic Range
Compression:
A major
problem for people with sensorineural hearing loss is discomfort as a result of
changes in sound intensity. Typically, patients' tolerance for low-frequency
sounds is different than their tolerance for high-frequency sounds. By accounting for these differences,
programmable hearing aids can be set so that low-intensity sounds will remain
audible, moderate-intensity sounds will be comfortably loud, and high-intensity
sounds will be loud but not uncomfortable for all frequencies. |
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Digital Sound Processing:
Completely digital devices provide the greatest degree of programming
flexibility and specificity.
Entering sound undergoes analog to digital conversion, is processed
within the hearing aid, and then is transformed back into sound by digital to
analog conversion. And of course, all of this is done in real time so that the
user does not notice a discrepancy between sound perception and the visual
aspects of speech. Because of digital capability, several devices with digital
signal processing provide the equivalent of a multi-channel graphic level
equalizer. |
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Directional Microphones:
By using
two separate microphones, one facing toward the front and the other facing
toward the back, hearing aids can effectively minimize distracting noise from
the back while emphasizing the desired signal from the front. This has been one of the most
substantial advances in hearing aid technology, because it directly addresses a
common and difficult complaint of patients with sensorineural hearing loss:
listening in a background of noise. |
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