Justification for Specific Hearing Aid Technology - A
Scot Frink presented this workshop at the Western Symposium on Deafness
(WSD) Conference in April 2005 in San Diego. Scot provided a good overview
of hearing aid technology and how a consumer should go about choosing an
appropriate hearing aid.
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article ;-) . So please do send them to email@example.com .
Here's what Scott had to say.
Hearing Aid Technology
Scot began his presentation with a review of the best hearing
technology over the last 100 years. His list included:
1902 - ear horn
1930 - body aid
1955 - behind-the-ear (BTE) hearing aid
1975 - in-the-ear (ITE) hearing aid
1980 - compression technology
1988 - programmable technology
1996 - digital technology
2000 - second generation digital technology
2004 - third generation digital technology
Scot then presented his thoughts on what technology can do. He included
miniaturization, improved sound quality, the control of loud sounds, and
better understanding in specialized listening situations, including
background noise, on the telephone, in the car, and hunting (where a
person with normal hearing wants to protect his ears from the noise of
shooting, but still be able to hear animals rustling in the bushes).
He also listed some things that technology can NOT do, including
restoring 100% of lost hearing, giving perfect intelligibility for soft
speakers, eliminating background noise, eliminating the need for
batteries, eliminating the need for repairs, and preventing moisture and
earwax from damaging hearing aids.
There are a variety of types of hearing aids available, and each person
should select an instrument that best suits her needs. Some helpful things
to keep in mind are that a digital hearing aid is not necessarily better
than an analog aid, a digital aid does not have to be expensive, and that
instrument cost and degree of hearing loss are important factors in
choosing an aid, but should not be the only factors.
One of the most common complaints people have about hearing aids is
their expense. There's no question that top of the line hearing aids are
expensive, but that's always true of the newest technology. The cost of
hearing aids employing older technology has actually decreased over the
years. For example, in 1996 a top of the line two-channel digital aid cost
$2500. The equivalent aid today (except that it has six channels instead
of only two) is $995. The bottom end has remained pretty flat. A basic
linear instrument that cost $495 in 1990 still costs $495 today. While the
price is constant in current dollars, today's instrument is considerably
less expensive if prices are adjusted for inflation.
Analog hearing aids will soon be phased out, as the market goes 100%
digital. Factors driving this trend include an easier assembly process,
reduced chip costs, and more easily addressed patient issues.
But note that one pair of digital hearing aids will cost $1600, while
another pair will cost $6000. So what's the difference? Among the most
important differences are the number of channels, differences in noise
reduction technology, different style choices, integration with wireless
technologies (e.g. FM and Bluetooth), and automation of features.
Selecting an Appropriate Aid
Several factors must be considered in selecting appropriate aids for a
particular individual. These include:
- Degree of hearing loss
- Hearing loss configuration
- Progressive nature of hearing loss
- Tolerance issues
- Background noise issues
- Specific needs of the individual
One of the first factors to be considered is the degree of hearing
loss. Greater hearing loss requires more powerful hearing aids. But modern
technology facilitates the construction of hearing aids that will benefit
virtually everyone with hearing loss. People with severe or profound
losses may find digital feedback managers particularly beneficial, because
they allow the hearing aid to provide increased power without producing
feedback. In general, more severe hearing losses require more power, which
means larger aids.
A second important factor in selecting a hearing aid is the
configuration of the hearing loss. A flat hearing loss (one with the same
loss at all frequencies) is the easiest to treat, requiring only a basic
amplifier. Such a hearing loss does NOT call for advanced technologies,
although other factors may.
Almost as easy to treat is the very common audiogram in which hearing
loss increases with frequency (high frequency hearing loss). This type of
loss is also well-treated with basic technology.
Complex and oddly-shaped audiograms generally require more advanced
technology. Such audiograms require different amounts of amplification at
different frequencies, so multi-channel instruments are appropriate
choices. In general the more complex the audiogram, the more channels are
required to adequately correct the hearing loss. These more problematic
losses include steeply-sloped losses, reverse slope losses, "cookie
bite" losses, and "reverse cookie bite" losses.
A third consideration in the selection of a hearing aid is the
progressive nature of the hearing loss. If a person's hearing loss is
progressive, she should select an aid that provides enough adjustment to
ensure that the aid will meet her needs for several years. While
conventional (analog) aids offer minimal adjustments, programmable aids
offer more, and digital aids even more. Some digital aids have upgradeable
circuits, which allow software upgrades to extend the life of the aid even
The first hearing aid with upgradeable circuits was introduced in 2000.
The initial circuitry included five channels, and did not include the
capability to adjust the noise reduction characteristics. A software
upgrade increased the number of channels to 20 and also provided for
adjustable noise reduction characteristics. During that same time, the
cost of that hearing aid fell from $2500 to $1900.
Note that choosing an aid that facilitates adjustments doesn't mean
you'll be able to use it forever. Wear and tear will eventually require
its replacement; smaller aids generally wear out sooner. The life
expectancy of a completely-in-the-canal (CIC) aid is about three years,
while a behind-the-ear (BTE) hearing aid should last five to seven years.