For
Our Patients
* Spoken Language is a natural and powerful system of human
communication. The Listening Center at Johns Hopkins provides
the medical, technical, and rehabilitative resources to enhance
our patients' connection with spoken language through listening.
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The Cochlear
Implant
Cochlear implants are small, electronic devices that provide awareness
and under standing of sound to those who do not enjoy the benefits
of sound with hearing aids. The cochlear implant employs a strategy
that is distinctly different from that of hearing aids. Instead
of amplifying and reintroducing the sound signal, the implant
bypasses impaired inner ear structures.
Sound energy is used to directly excite the nerve of hearing.Electrical
contacts placed within the cochlea send signals to the hearing
nerve. These sig nals form a code based in those features of speech
that are critical to word understanding in normal listeners. Either
through a process of learning in the early, formative years or
by virtue of "hearing memory," the brain is capable
of interpreting this code to enable speech understanding and appreciation
of the surrounding soundscape.
When we talk about a "cochlear implant" we are actually
referring to a system of technologies that process and transmit
information. There are four components of the system:
1. An external microphone picks up sound from the environment.
2. An external speech processor (a computer) translates
the energies contained in
incoming sounds picked up by the microphone into a code that the
brain can understand.
The processor is worn either behind the ear or on a belt.
3. An external transmitter is magnetically attached and
worn behind the ear and under the hair. The transmitter sends
coded information that is based in sound to the internal receiver/stimulator.
4. An internal receiver/stimulator, about the size of a
quarter, is placed under the scalp, behind the ear.
It relays sound information from the internal receiver to the
inner ear via wire circuits that are threaded into the cochlea.
Signals transmitted down the wire directly stimulate the nerves
inside the cochlea, creating a train of impulses conveyed to the
brain to produce what we know as "sound."
HOW THE COCHLEAR IMPLANT ENABLES HEARING
Even when hearing loss is severe and early in onset, the hearing
nerve survives and retains responsiveness to electrical currents.
This means that excitation of the hearing nerve is possible.
A cochlear implant stimulates the hearing nerve with a sophisticated
code. The code developed is within a speech processor that selects
the important features of incoming sounds. The code is then presented
across channels placed within the cochlea and enables the implant
listener to perceive different pitches.
Variations in the power and tempo of the electrical signals convey
various sounds by triggering different patterns of impulses in
the hearing nerve. Hearing stations within the brain receive and
coordinate these impulse trains, resulting in the perception of
sound and the ability to distinguish differences in pitch, power,
and tempo.
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The
Benefits of Cochlear Implantion
An individual or a family
might consider a cochlear implant to address any of a number of
concerns. Whether it is a family's goal for a child born deaf
to develop verbal language, a parent with progressive hearing
loss who wishes to monitor the safety and speech of their hearing
child, or a grandparent with advanced hearing loss who desires
to hear the voices of younger generations, the motivations for
restoring hearing vary widely. As a result, there are many definitions
of success with a cochlear implant. However a combination of personal
motivation and effective guidance are common to all stories of
success.
Although a cochlear implant potentially offers a range of benefits,
The Listening Center attempts to help users develop a meaningful
connection to the world of sound. To achieve that goal, The Listening
Center has found that dedicated training with a cochlear implant
is essential.
With training, a child or an adult with a cochlear implant
can learn to:
• understand and use spoken language,
• monitor personal speech to improve clarity
and intonation, and
• detect and understand the meaning of sounds
in the environment.
Because many communication cues within everyday speech escape
visual detection, cochlear implants restore a level of access
to spoken language that can immeasurably improve quality of life.
More than two decades of experience has shown, however, that
three basic factors need to come together in order to realize
the potential benefits of a cochlear implant:
• safe, early intervention,
• enhancement of the device's function with precise
programming, and
• training of the recipient in the skills of
communication.
A cochlear implant will most benefit individuals who:
• have inner ear hearing loss and limited speech
understanding with properly fit hearing aids,
• have lost hearing after initially developing
listening skills or have had severe hearing loss for a short period;
in children with early hearing loss, the likelihood of optimal
benefit increases if the implant is provided at an early age,
and
• possess sufficient motivation or a motivated
support system (e.g., parents or family) to build on the awareness
of sound and ultimately comprehend the complexities of voiced
and environmental sounds.
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What
is hearing?
Sound waves funneled into
the ear cause he tympanic membrane (eardrum) to vibrate. These
vibrations
cross a tiny bridge formed by the three smallest bones in the
body to the cochlea of the middle ear.
The fluid - filled cochlea detects sound waves by means of microscopic
structures know as hair cells.
The hair cells respond to sound waves be triggering impulses in
the hearing nerve which in turn transmits a signal to the brain.
The brain interprets this signal as sound.
Most profound hearing loss in sensorineural in nature - there
is damage to the sensitive and vulnerable hair cells in the cochlea.
Sound waves are lost or distorted and cannot be transmitted throuigh
the hearing nerve to the brain. Cochlear implants bypass the damaged
hair cells by stimulating the auditory nerve directly.
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Candidacy
Children
and adults with an advanced level of sensorineural hearing loss
in both ears may benefit from a cochlear implant. A cochlear implant
may be considered for someone with a hearing loss that is severe
enough to limit speech understanding, even with well-fit hearing
aids. The inability to hear more than one half of amplified words
provides a guide that helps define candidacy.
Success with a cochlear implant begins with carefully planned
evaluations. These include medical, audiological, psychological,
and communication testing to help ensure that a candidate is likely
to derive benefit from a cochlear implant. Both childhood and
adult candidates must have experience with hearing aids. Training
,,, basic communication skills is also helpful in some cases before
a cochlear implant is placed.
The assessment of candidacy will evaluate a range of factors now
known to be important, if not crucial to success. A cochlear implant
candidate's ability to attend to sound, to make meaningful associations
with sounds, and to integrate hearing into social interactions
will ultimately reinforce use of the device. Skills in problem-solving,
attention, and memory can further strengthen communication abilities
after a cochlear implant is placed. The emotional experience of
learning to hear with a cochlear implant is significant. Thus
the psychological assessment of candidates and families often
provides important insights into how best to tailor a complete
plan of intervention.
Counseling informs candidates and their families of what to expect.
A realistic expectation of what a cochlear implant can provide
is the starting point at which successful use of a cochlear implant
may begin.
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Device
Choice
The
Listening Center has actively participated in clinical trials
of new generations of devices that emerged with refinements in
implantable circuits beginning in the early 1990's. Research and
clinical experience ained at The listening Center spans the development
and use of several developing technologies.
During candidacy evaluations the audiologist presents information
on available devices, highlighting the features that can help
guide the choice. As one of the largest implant centers in the
United States, The Listening Center has been at the forefront
of technological advances and clinical practice, providing patients
with a full range of device options.
* The Listening Center does not accept advertising
funding from any implant device company. We give our patients
the options of all the specific brand of implant device. We
will only suggest a specific device if, during candidacy, we
identify a reason that prompts the need for that particular device.
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Surgery
Cochlear
implant surgery is performed as outpatient surgery under general
anesthesia and requires between one and two hours. Because the
size of the cochlea remains unchanged during development, children
receive the same implant as adults. Surgical access to the inner
ear is accomplished with minimally invasive techniques and vigilant
monitoring of neighboring nerves, thus allowing for a safe and
effective operation and a short recovery time.
With advances in implantable electronics and surgical techniques,
Listening Center ear surgeons and audi ologists have been at the
forefront of an area of cochlear implant research that holds great
promise in improving performance: Enhancing the ability to excite
small, selected populations of fibers within the hearing nerve
with a cochlear implant. This approach mimics the process of activation
that occurs in normal hearing. As the ability to discretely stimulate
nerve fibers continues to improve, so too does the quality of
the listening experience.
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Activation
& Programming
The system is activated
after a period of healing, providing recipients their first opportunity
to hear through the cochlear implant. While most individuals do
not understand speech through the implant at first, activation
marks a time of change and opens a new life chapter.
Sounds that are heard are adjusted in a process called mapping.
The audiologist uses a computer to set a volume level for each
of the implant's stimulating contacts to provide the most sensitive
and the most comfortable levels of stimulation.
The object of cochlear implant mapping is optimize the perception
of sound. As new cochlear implant recipients learn and gai. experience
hearing with their device, Listening Center audiologists then
reprogram and fine tune the implant. After initial adjustment
to the cochlear implant, the hearing pathway gradually becomes
more sensitive and effective. As the ability to use the implant
improves over time, finer adjust ments are made in order to enhance
the quality of the perceived sound.
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Cochlear
Implants in Children
Learning to use a cochlear implant to great effect is seen most
dramatically in young children, but many of the same principles
of learning apply to adults.
Indeed, experience with hundreds of children and adults has enabled
The Listening Center to apply insights gained in one group to
the other, allowing both to take the experience of listening with
a cochlear implant to its fullest potential.
The Listening Center is committed to the following principles:
Early intervention yields the best results
Studies show that early implantation is important for producing
optimal results in children with deaf ness. For example, sensitive
hearing is achieved early in the vast majority of these children.
However, it is the degree to which restored hearing turns into
language that best defines success with a cochlear implant. Speech
and language skills develop more readily when a child hears spoken
language early in life. From birth through early childhood stages,
children's neural pathways develop in a manner that is shaped
by their sensory experience. The shorter the period of deprivation
of sound, the better the results from cochlear implantation.
Rehabilitation maximizes the potential of children who receive
cochlear implants
Sensitive hearing is necessary but not sufficient for understanding
spoken language and producing speech that is easily understood
by others. While the cochlear implant provides access to sound,
understanding takes more than just hearing. Rehabilitation provides
a structured approach to learning to identify and associate meaning
with unfamiliar sounds, thereby allowing spoken language skills
to develop.
Families and professionals need to act as a team soon after
a diagnosis of deafness in a child
Children with cochlear implants are more likely to gain sophisticated
communication skills when fam ilies and professionals collaborate.
The Listening Center works in partnership with parents, teachers,
therapists, and physicians to ensure continuity of the training
offered at the Center into the daily life of the child with a
cochlear implant.
REHABILITATIVE SERVICES
Rehabilitation is as essential to success with a cochlear implant
as the surgery and device programming. Our rehabilitation team
consists of well-trained and highly experienced speech language
pathologists and deaf educators who collaborate to facilitate
the child's development of auditory skills, spoken language, and
educational achievement.
In addition to providing cochlear implant rehabilitation, our
staff communicates directly with our implant audiologists in reviewing
a child's progress and programming needs, collaborates with parents
and school personnel, and provides direct classroom observation
of children in the school setting. The Listening Center's rehabilitative
therapists have extensive experience with auditory rehabilitation
and spoken language development and maintain a high standard of
continuing education specific to cochlear implantation.
DIRECT THERAPY
The cochlear implant provides the child with the ability to detect
all of the sounds of speech. Auditory training is the key that
unlocks a child's ability to make sense of the sound provided
by the implanted device. The training naturally encourages skills
such as detection, imitation, and association of meaning with
the sounds of spoken language.
As part of the candidacy process, The Listening Center team gathers
baseline information about speech, language, and auditory skills
development. This knowledge allows the rehabilitation
therapist to coordinate care with implant audiologists to ensure
that each child has a finely-tuned implant to maximize his or
her developing skills.
Auditory rehabilitation sessions at The Listening Center establish
a collaborative partnership between the family and therapist.
Goals and objectives developed during these sessions pro vide
mutual focus for nurturing development in all areas of a child's
life. Ongoing support to parents establishes a path to success
for the child.
PARENTAL SUPPORT
Parents are a child's first and most important teachers. The Listening
Center empowers parents with understanding of the principles of
auditory skill development, communication, speech and language
development, and strategies of behavioral modification that promote
attention and focus. Even in the routine of a normal day, language-rich
experiences can be plentiful.
EDUCATIONAL SUPPORT
Collaboration between the home, school, and The Listening Center
ensures a unified effort to optimize the child's listening and
communication potential.
The Listening Center partners with teachers and support personnel
to provide an optimal listening environment, promote language
growth, and main tain the function of the cochlear implant system.
The following support and training are available to school professionals:
• Pre-implant assessments: Speech & Language;
Auditory Skills Development
• School-based, in-service instruction for teachers
and staff
• Individual Family Service & Individual
Education Plan Development
• Observations and recommendations for strategies
to be used in the classroom and in therapy
• Videotaping and analysis of communication styles
and educational needs
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Rehabilitation
Recognizing that effective communication is a lifeline to meaningful
interactions with family and friends, to a rewarding career, and
to successful aging, The Listening Center offers rehabilitation
services tailored to the unique needs of the adult cochlear implant
user. The rehabilitation program includes counseling, auditory
training, and instruction in communication management.
In addition, a comprehensive approach to individual programming
needs is accomplished by close collaboration between the therapist
and the implant audiologist.
Counseling begins during the candidacy process and continues after
cochlear implantation. We begin by providing information to guide
expectations related to use of the cochlear implant and the auditory
envi ronment. This service is available to individuals, their
family members, and personnel within educational and employment
settings.
Rehabilitation consultation shortly after activation of the cochlear
implant provides assessment of the early level of functional communication
skills. On the basis of early results, The Listening Center's
staff will deter mine whether auditory rehabilitation will provide
further opportunities.
Auditory rehabilitation emphasizes the interaction of sound and
language information to teach the adult to recognize the spoken
messages in everyday listening situations. For example, newly
acquired skills may be applied to functional use of the telephone
as guided by emerging speech recognition abilities.
Training in communication skills enhances the ability to manage
interpersonal and group listening situa tions. By understanding
the impact of the environment, the speaker, and the listener,
an individual can develop successful communication strategies.
Strategies for difficult listening situations are practiced and
options for assistive devices are explored. With guidance, implant
listeners can use the technological capa bilities of the device
to their fullest advantage.
Every recipient presents a unique hearing history and an indi
vidual level of skill in verbal communication. The program of
training and rehabilitation after a cochlear implant should reflect
the unique needs of the implant listener. Our rehabilitative approach
is thus individualized and modified as progress is made.
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