A cochlear implant is an electronic device that can restore useful hearing and provide improved communication abilities for individuals who receive little or no benefit from hearing aids. A cochlear implant transforms sound into electrical signals and uses that signal to bypass damaged portions of the inner ear and directly stimulate the hearing nerve. The number of patients implanted annually continues to rise as a result of expanding candidacy criteria for implantation as well as new developments in cutting-edge cochlear implant technology.
Collectively, the members of our cochlear implant team have extensive experience working with cochlear implant candidates and recipients. Our goal is to bring meaningful sound to the lives of individuals who are deaf or hard of hearing through a partnership of medicine, technology, rehabilitation and advocacy.
As of 2018, there are two types of cochlear implant devices available: traditional cochlear implant systems and hybrid cochlear implant systems. Traditional cochlear implant systems are for people with ‘moderate’ to ‘severe to profound’ sensorineural hearing loss in each ear. Hybrid cochlear implant systems are for people with ‘normal to moderate’ sloping to ‘severe to profound’ sensorineural hearing loss. Hybrid technology gets its name from combining cochlear implant technology and hearing aid technology in one device.
There are a number of cochlear implant devices currently available, and our cochlear implant team will discuss these options with you. All systems, including traditional and hybrid cochlear implants, consist of an external piece called the speech processor and an internal piece that is implanted in the cochlea.
The cochlea is a tiny snail shell-shaped organ that is comprised of thousands of microscopic sensory cells. These sensory cells work like keys on a piano. Each sensory cell is organized and tuned to match a certain pitch. These sensory cells respond to acoustic information in the environment and translate it into a neurological code that the brain can interpret. If any of the sensory cells are damaged and/or missing, the information that arrives in the brain will be distorted and incomplete. Understanding of sound happens in the brain; the ears are just the way in. The sensory cells have a very important role in this translation of acoustic information to a neurological code. If any of the sensory cells do not work properly, the information that arrives in the brain will be distorted and incomplete. This causes the listener to work even harder to understand what he or she is listening to.
Speech is a complex acoustic signal. When a speech signal makes it to the cochlea, many sensory cells respond. This would be analogous to a sonata playing on a piano. Many keys are being played at once to make rich, full music or, in this case, speech. When sensory cells are damaged and/or missing, incomplete and distorted sound arrives at the brain. Think about how a piece of music would sound when played on an out-of-tune piano with missing keys. This is comparative to speech coming through a cochlea with damaged and missing sensory cells. When the signal arrives at the brain, the music isn’t rich, full, or even recognizable. The listener has to work even harder to understand what he or she is listening to.
Cochlear implants are designed to bypass the sensory hair cells of the cochlea that are not functioning and provide direct stimulation to the auditory nerve which transmits signals from the inner ear to the brain.
There are two parts to a cochlear implant system: the internal device and the external device. The internal device of a cochlear implant is surgically implanted in the temporal bone, and the external device is worn externally behind the outer ear, much like a behind-the-ear hearing aid.
Internal Device – The surgically implanted internal device consists of a receiver/stimulator and an electrode array. The receiver/stimulator is surgically implanted under the skin behind the ear. The electrode array is placed inside the cochlea (inner ear).
External Device – The external device consists of a speech processor and a headpiece that connects to the internal device by a magnet.
The cochlear implant system takes in sound through the speech processor (external device), translates it into an electrical signal, and delivers it to the receiver/stimulator (internal device). The internal device sends the appropriately mapped code to the electrode array, which then sends electrical impulses to the auditory nerve. The auditory nerve then sends the signal to the auditory cortex, allowing the brain to interpret this new type of signal.
A cochlear implant is not a hearing aid. Rather, it is a device that sends electrical stimulation to the auditory nerve, bypassing those damaged sensory cells when hearing aids do not provide speech understanding.
In general, if someone wearing appropriately fit hearing aids cannot understand speech without seeing the speaker’s face, they should be evaluated for a cochlear implant. Research is constantly providing new information and technology resulting in changes in cochlear implant procedures and instrumentation. Cochlear implants help people who simply are not getting enough benefit from hearing aids. The following statements can help determine if you are a cochlear implant candidate:
- I have difficulty following conversations without lip reading.
- I hear pretty well in quiet, but I struggle in groups or noisy places.
- I cannot follow most phone conversations; especially if I do not know the person calling.
- I feel isolated and limited both socially and occupationally due to my hearing loss.
If you answered “Yes” to any of these statements, you may benefit from a cochlear implant. Contact us at (317) 842-4901 to schedule an evaluation to determine if you are a candidate for a cochlear implant.
There are no upper age limits to cochlear implantation. In fact, about one third of our patients are above the age of 65.
Children can also be candidates for cochlear implants. Children as young as 12 months of age have received cochlear implants, and the potential exists for successful implantation at younger ages. For children, an assessment of any child with a severe to profound hearing loss should be made as early as possible as outcomes with a cochlear implant are significantly better in children who receive an implant at the earliest possible age.
It is generally agreed that the best child candidates are those who:
- Have severe to profound hearing loss in both ears
- Can receive little or no useful benefit from hearing aids
- Have no other medical conditions that would make the surgery risky
- Are involved (when age appropriate and able), along with their parents, in all aspects of the informed consent process
- Understand (when age appropriate and able), along with their parents, their individual roles in successful use of cochlear implants
- Have (when age appropriate and able), along with their parents, realistic expectations for cochlear implant use
- Are willing to be involved in intensive rehabilitation services
- Have support from their educational program to emphasize the development of auditory skills
- Improved awareness of sound
- Detection of sounds in the speech range (but not speech understanding)
- Detection of music
- Improved speech reading ability
- Awareness of one’s own voice
With training, a cochlear implant user may be able to develop these further hearing capabilities:
- Detection and understanding of the meaning of sounds in the environment
- Understanding of spoken language
- Development of speech
- Monitoring of volume and clarity of speech
Cochlear implant recipients receive extensive rehabilitation services from audiologists. Some adults may also benefit from speech-language therapy. Children should be enrolled in speech-language therapy at the diagnosis of hearing loss, and continue this therapy after cochlear implantation.
Your offsite audiologists will assist in how to use the implant and how to respond to the sounds your new cochlear implant is providing. For those who have heard before, sounds through the cochlear implant may seem unnatural at first. Many cochlear implant users say that voices resemble cartoon characters, or that speech is unintelligible at first. However, with practice many cochlear implant patients are able to understand speech in quiet environments and many note significant improvement in noisy situations. Adults who have never heard must be taught what the sounds are, and may only use a cochlear implant system to gain awareness of environmental sounds. Children, when implanted at an early age, often reach the levels of their normal hearing peers in speech, language and hearing development with extensive speech-language and aural rehabilitation therapies.