Breaking the Sound Barrier
by Jen Mundl
Lisa sat quietly in the classroom
not participating in conversations around her. Her teacher originally
thought Lisa was shy, until one day he was talking to her and she
did not respond. A hearing test showed a significant hearing loss
to where she was unable to recognize sounds and language. That explained
a lot. Luckily for Lisa, her teacher noticed and her difficulties
could be addressed with assistive technology. (Unfortunately, too many students
like Lisa remain undiagnosed.)
To understand assistive technologies, it is useful to know a little
about sound. Sound is measured in two ways: by its loudness or intensity
(measured in units called decibels, dB) and its frequency or pitch
(measured in units called hertz, Hz). Impairments in hearing can
occur in either or both areas, and may exist in only one ear or in
both ears. Hearing loss is generally described as slight, mild, moderate,
severe, or profound, depending upon how well a person can hear the
intensities or frequencies most greatly associated with speech. Generally,
only people whose hearing loss is greater than 90 dB are considered
deaf.
Types of Hearing Loss
Physiologically
speaking, hearing loss is classified into two categories. Conductive
hearing losses are caused by diseases or obstructions in the outer
or middle ear (the conduction pathways for sound to reach the inner
ear). Conductive hearing losses usually affect all frequencies
of hearing evenly and do not result in severe losses. A person with
a conductive hearing loss is usually well-served with a hearing
aid or can be helped medically or surgically.
Sensorineural hearing
losses result from damage to the delicate sensory hair cells of
the inner ear or the nerves which supply them. These hearing losses
can range from mild to profound. They often affect the person’s
ability to hear certain frequencies more than others. Thus, even
with amplification to increase the sound level, a person with a
sensorineural hearing loss may perceive distorted sounds, sometimes
making the successful use of a hearing aid impossible.
A mixed hearing loss refers to a combination of conductive and sensorineural
loss and means that a problem occurs in both the outer or middle
and the inner ear. A central hearing loss results from damage or
impairment to the nerves or nuclei of the central nervous system,
either in the pathways to the brain or in the brain itself.
Accommodations
Lisa’s
diagnosis was a conductive hearing loss resulting from reoccurring
untreated ear infections. Lisa worked with audiologists and doctors
to find ways for her to interact more successfully in the classroom.
One audiologist suggested she use an Assistive Listening Device that
amplified the speech of the teacher directly into her new digital
hearing aid. It did the trick and soon Lisa began laughing with her
classmates.
Accommodations and assis-tive
devices are required by many people with hearing impairment to
access the educational programming in a classroom setting, communicate
with others and work effectively with coworkers. Each person’s
needs must be individually evaluated, but the following is a generic
introduction to the main types of assistive technology for people
with hearing impairments.
Assistive Listening Devices
Assistive listening devices
include a large variety of technologies designed to improve audibility
in specific listening situations. Some are designed to be used with
hearing aids or cochlear implants, while others are designed to be
used alone. Many that are used in conjunction with hearing aids require
a telecoil (T-switch).
Assistive listening
devices can usually amplify a signal, but their primary purpose
isn’t to make a signal louder. Rather, they
place a microphone close to the sound source, so that it becomes
louder compared to the other sounds in the environment. Assistive
listening devices improve the ability to hear because they make the
desired sound stand out from the background noise.
Closed Captioning
Closed captioning
is the text that goes on the bottom of the television screen to inform
deaf or hard of hearing people of what is being said. Look for a
small box with letters “CC” inside
of a small box with a cartoon balloon dialogue marker, to verify
if the programs are closed captioned.
Cochlear Implants
A cochlear
implant is used for people with severe to profound hearing loss
or those who show little or no benefit from hearing aids, yet have
some hair follicles. It is a controversial device, especially when
it is implanted in young children. This very tiny piece of electronic
equipment is put into the cochlea during an operation. It takes
over the job of the damaged or destroyed hair cells in the cochlea
by turning sounds into electrical signals that stimulate the hearing
nerve directly.
Hearing Aids
Hearing aids are similar
to tiny microphones—they
help someone hear sounds better through amplification. Hearing aids
deliver amplified sounds (via sound vibrations) from the eardrum
and middle ear to the inner ear or cochlea. Hearing aid technology
is available that can adjust the volume of sounds
Hearing Loop
A Hearing Loop
is a coil of wire that amplifies sound and reduces background noise.
Users of hearing aids with a loop can set their aids to a certain
setting to receive the transmission. Hearing loops can be permanently installed
or portable.
Text Telephones
Text Telephones
(TTYs) are one communication option for people who are deaf or
hard of hearing. These devices look like small typewriters and come
with an LCD screen and a cradle for the telephone. In order for a
person to call on the TTY, the person on the other end must also
have a TTY. There is also a national relay system which allows the
person on the TTY to call someone who does not have a TTY. They system
also allows people using mobile phones and pagers to send emails,
faxes, pages and call people who have TTY.
Visual Alert Signalers
Visual
Alert Signalers are devices that use flashing lights to alert the
person who is hard of hearing or deaf to the ringing of a phone
or fire alarm or other device.
Conclusion
The above list is
only a sample. There are many more assistive technology devices available
for people who are hard of hearing. Many of these devices—such
as text messaging and e-mail—have infiltrated mainstream society. You
can find out more by researching the topic on the Internet. There are excellent
Web sites explaining how the technologies work, how to have them evaluated,
and where to buy them.
