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Some new hearing
aid features can be confusing because of the specialized terminology
used to describe them. Different options include: programmability,
multiple frequency bands, multiple listening programs, digital signal
processing, and remote controls. These are available in most styles of
hearing aids, including the tiny "Completely in the Canal" aids, and the
powerful "Behind the Ear" aids. Just what are these features?
Programmability
Programmability refers to the ability of your audiologist to change the
parameters of your hearing aid in the office without sending it back to
the factory. Some programmability has been available for a long time
using potentiometers (variable resistors) built into the hearing aids.
These resistors can be adjusted by screwdriver, however the number of
parameters that can be adjusted is limited by the number of
potentiometers that can be put in a reasonably sized hearing aid.
The programmable hearing aids getting most of the attention now are
programmed by computer in your audiologist's office. This allows many
parameters to be changed, even in tiny hearing aids like the Completely
in the Canal aids. Also it allows the audiologist to let you try several
listening programs, and to be able to go back to the program you like
best, even a long time after the first adjustment was made. These aids
also allow your audiologist to adjust the sound of your hearing aid as
your hearing preferences change over time.
These hearing aids are sometimes called "Digital" because they are
programmed by digital computer. They are just analog hearing aids
inside, however.
Multiple
Frequency Bands
Some
hearing aids have multiple frequency (pitch) bands, with different
parameters for each band. For example, your ear might find loud
mid-frequency sounds more objectionable than loud high-frequency or low
frequency sounds, and a three frequency band programmable aid could be
adjusted to accommodate this by having different gain settings in the
different bands. Each band could have its own amplification, compression
limiting, or dynamic range settings. The audiologist can adjust the
position (edge frequencies) of each band as well as the other
characteristics of some of these aids.
A simple version of this could be an aid with two bands, one high
frequency and one low frequency. The aid might have automatic volume
controls set to cut the amplification in the high frequency band in the
presence of loud noise without changing the amplification of the low
frequency band. This would be good for many noisy situations. The
industry name for this kind of circuit is "K amp" and it is available in
many different brands of hearing aids.
Multiple
listening programs
Some
hearing aids have more than one group of settings. A simple one-program
hearing aid can be set for the listening situation that bothers you the
most, or perhaps the one where you spend most of your time, such as near
a noisy air conditioner in your office.
Multiple-program hearing aids can be switched between programs whenever
you like. For example, you might have one program for quiet conversation
or music, and another for noisy situations where communication is
difficult. Some hearing aids have many different programs. More programs
are not necessarily better however, because switching between them and
keeping track of which program you are using can be a bother. You switch
between programs by pushing a button on the hearing aid or by using a
remote control.
Remote
Controls
Yes, even
hearing aids can have remote controls, just like your television set.
The remote controls typically are about the shape of a credit card and
as thick as a pencil and operate by infrared light or radio signals. The
radio control units can stay in your pocket or purse while you operate
them.
These remote controls typically control loudness, and listening program
(such as "for noise" or "for music"). Some even have tone controls and
telephone switches in them. One brand has a zoom feature that can focus
the listening field to the front when you want. Most can adjust both
hearing aids at the same time.
Digital
Signal Processing
True
"digital" hearing aids have just entered the market in the last few
years (and are described in
more
detail on another page of this web site). The word "digital" has
been used with hearing aid marketing for some time, but in the past it
referred to the ability to program the aid "digitally", not that the aid
used digital signal processing. Now, some new hearing aids do use
digital signal processing to improve the signal to noise ratio and to
process the sound signals. The real breakthrough was in being able to
manufacture dsp chips that are able to operate on tiny hearing aid
batteries for a reasonable amount of time.
Wireless
Recent hearing aids include wireless hearing aids.
One hearing aid can transmit to the other side so that
pressing one aids program button simultaneously changes
the other aid and both aids change background settings
simultaneously. FM listening systems are now emerging
with wireless receivers integrated with the use of
hearing aids. A separate wireless microphone can be
given to a partner to wear in a restaurant, in the car,
during leasure time, in the shopping mall, at lectures,
or during religious services. The voice is transmitted
wirelessly to the hearing aids eliminating the effects
of distance and
background noise. FM systems have shown to give the
best speech understanding in noise of all available
technologies. FM systems can also be hooked up to a TV
or a stereo.
The Future
These
features are available in hearing aids now. The first nearly invisible
"Completely in the Canal" aids appeared just a couple of years ago, and
now nearly all manufacturers offer them. Two manufacturers introduced
digital signal processing to hearing aids about 3 years ago. Now many
more brands offer true dsp hearing aids. You can expect hearing aids to
continue to get smaller, to have more features, and to provide better
hearing. Hearing aids are really better now than they were just a few
years ago.
Cochlear
implants, which are a form of hearing aid, are gaining wider acceptance
in spite of their cost and long training requirements. A Cochlear
implant is a bundle of tiny wires that is inserted surgically into the
inner ear. The electrodes are connected to a processor by a
transformer-like connector and magnet implanted behind the ear. The
signal processor (usually mounted on the patient's belt and connected to
the ear by a wire) drives the electrodes using sounds picked up by a
microphone near the ear. With training, people who have lost their
hearing after first having at least some hearing early in life, can
learn to interpret the stimuli as sounds and some seem to be able to
hear quite well. Two manufacturers have announced models that put a
simplified processor in a BTE-like case over the ear, eliminating the
need for signal processor on the patient's belt.
Hearing aids are far from perfect, and people with hearing loss cannot
expect to hear as well as people with good hearing, even with the best
hearing aids made. You should always try to protect your hearing,
because technology cannot fix lost hearing, not now, and probably not in
the future either.
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