the range of frequency and pitch the ear can
detect through amplification and modulation.
Hearing aids are most effective in sensorineural
hearing loss and can improve hearing in one ear
or both ears.
Kinds of Hearing Aids
There are five kinds of hearing aids in common
use today:
- Completely in the canal (CIC) hearing aids are
the smallest available and fit well into the audi-
tory canal. They are barely visible when in
place. CIC hearing aids are most effective for
mild to moderate hearing loss. People who
have small auditory canals or limited manual
dexterity may not be able to use CIC hearing
aids. CIC hearing aids allow the wearer to use
the telephone without adaptive devices. - In the canal (ITC) hearing aids fit into the
start of the auditory canal. A bit larger than
CIC hearing aids, ITC hearing aids are some-
what noticeable when in place. They are easier
to handle than CIC hearing aids and also are
most effective for mild to moderate hearing
loss. - In the ear (ITE) hearing aids fit at the opening
of the auditory canal and are visible on the
outer ear (auricle). The larger size of ITE hear-
ing aids give them the capacity to contain larger
amplifiers, extending the range of hearing loss
they can accommodate. ITE hearing aids are
effective for mild to moderately severe hearing
loss. - Behind the ear (BTE) hearing aids drape over
the external ear (auricle), with the housing for
the electronics and battery behind the ear. A
thin tube runs from the BTE hearing aid over
the front of the auricle and into the auditory
canal. BTE hearing aids accommodate the
broadest range of hearing loss because they can
hold larger amplifiers and the larger batteries
necessary to provide power. - Implantable middle ear devices are surgically
implanted in the middle ear. They attach to and
directly stimulate the auditory ossicles, the tiny
bones in the middle ear that amplify and trans-
mit sound to the inner ear. There are two varia-
tions of implantable middle ear devices, one
that is completely implanted (with the receiver
embedded in a pouch of tissue behind the ear)
and one that has internal and external compo-
nents (the receiver hangs behind the ear).
Implantable middle ear devices accommodate
moderate to severe hearing loss and typically
become an option when conventional external
hearing aids are ineffective.One other style, the body hearing aid, attaches
to the belt or fits within a pocket. About the size
of a cellular phone, the body hearing aid can con-
tain a very large amplifier and comparable battery
to power it. Wires run from the body hearing aid
unit to the ears. Though significantly less conven-
ient than other styles of hearing aids, the body
hearing aid can make limited HEALINGpossible for
people with profound hearing loss.
BTE hearing aids can be analog or digital; CIC,
ITC, and ITE hearing aids and implantable middle
ear devices are digital. Analog units receive
incoming sound waves and transmit them directly
to the amplifier; they make sound only louder.
Many people consider analog technology out-
dated, though it nonetheless provides improved
hearing across a broad spectrum of hearing loss.
Some analog hearing aids have manual volume
controls and others can accept a wider range of
adjustment via computer programming. Digital
hearing aids convert incoming sound waves to
binary signals that are much faster to process elec-
tronically. Many digital models use computer
microchips to allow a broad range of customized
adjustments that can filter out certain sounds
(such as background noise) and independently
enhance or subdue specific frequencies of sound.
Digital hearing aids are programmable and provide
sounds closer to natural hearing, though they are
significantly more expensive than analog hearing
aids. For many people cost is a framing factor in
choosing a hearing aid because most health insur-
ance plans do not provide coverage for hearing
aids.
Adjusting to Hearing Aids
Hearing aids cannot replace natural hearing or
restore the function of hearing to normal. Simplis-
tically, hearing aids overstimulate the remaining
sensorineural structures of the inner ear so they
can respond to sound signals. People using hear-hearing aid 27