Introduction to Cochlear Implants
Cochlear implants compensate for damaged or non-working parts of the inner ear. The inner ear converts sound waves into electrical impulses. These impulses are then sent to the brain. A cochlear implant works in a similar manner. It electronically finds useful sounds and then sends them to the brain. Hearing through an implant sounds different from normal hearing. However, cochlear implants allow many people to communicate orally in person and over the phone.
Cochlear Implants and Hearing
In order to understand how a cochlear implant works, it is important to understand how we hear. The outer ear collects sound waves and sends them to the middle ear. The sound waves bounce off your eardrum and are made louder by three tiny bones: the hammer, anvil, and stirrup. The sound waves travel into the fluid filled inner ear. The waves go through the cochlea (the organ of hearing). Microscopic hair cells in the cochlea turn the vibrations into electrical impulses. Then your brain receives and interprets this energy as a sound or speech.
Cochlear implants take advantage of the things an ear can still do after hair cells have been damaged or destroyed. It also takes advantage of how smart and flexible the human brain can be. The cochlear implant creates a new way of hearing. A cochlear implant consists of five basic parts; these are a microphone, a speech processor, a transmitter, a receiver/stimulator, and an electrode array.
(Image shows Advanced Bionics Harmony sound processor and implant, for more information please visit www.advancedbionics.com and www.advancedbionics.com/bea)
Expectations
Children should be involved in a program which emphasizes listening and speaking skills. High motivation, positive family environment, and realistic expectations are all important for success.
A comprehensive evaluation is necessary to determine if a child is a candidate for a cochlear implant. This may include the following evaluations: hearing, speech, language, balance, medical, and psychosocial. Any surgery involves risks, particularly when it involves young children. These risks must be discussed thoroughly with your medical team. The implant may affect other medical procedures in the future.
The decision to choose a cochlear implant must be made after carefully weighing all of the pros and cons. There are usually a wide range of emotions, conversations and research that contribute to that decision. The benefit a child may obtain from a cochlear implant is difficult to predict. Many resources show children with implants who are very skilled listeners and speakers. Parents must remember that implants are tools, not miracles. Not every child with an implant performs in the same way. Reasonable expectations may include improved detection of sounds and speech. Some children with implants have an increased awareness of sound and can detect and recognize sound patterns. Other children are able to understand speech through listening alone. Even these children, however, benefit from speech reading cues and assistive listening devices particularly in noisy places. Learning how to use an implant requires the child, family and support system to work together. It takes a lot of practice to recognize and understand sounds and speech. “It’s been said that the cochlear implant is 10% hardware and 90% software. And the software is us.” By involving siblings and other family members you can build a better understanding of the child's needs. Although sometimes astounding things happen, most changes occur in small steps.
Surgery and Activation
A surgeon puts the receiver/stimulator and the electrode array under the skin behind the ear and into the skull. The surgeon threads the electrode array into the cochlea past the damaged hair cells. Surgery lasts from 2-3 hours. Most children resume normal activities within days after surgery. It generally takes 3 to 5 weeks for the incision to heal. The device is activated at the clinic 4 to 6 weeks after surgery. The process of adjusting the cochlear implant system to meet a child’s needs takes time. Adjustments will require numerous clinic visits. As the child’s use of the implant changes, adjustments are also made. This process of adjusting the output of the system is called mapping. Children with cochlear implants can participate in all common childhood activities. The transmitter (on the outside of the skin) is magnetically held to the receiver (located just under the skin). It is quick and easy to remove the external parts for activities like swimming or bathing.
Follow up and Rehabilitation
Between 4 to 6 weeks after surgery the implant will be activated. Implant activation may be either a one or two-day process. Activation of the device does not produce “instant” hearing. Many return visits may be needed within the first year. These visits will be for both fine-tuning the speech processor and auditory training or aural rehabilitation. Follow your therapist’s recommendations about using a hearing aid in the non-implanted ear. The surgery is merely the beginning. The real work is to help the child learn to listen. Signals from the implant are used to recognize, understand, and produce speech. The child will also learn to identify and use environmental sounds. This is typically a slow process with many small steps. The child, family, therapists and educators must work together to achieve success. It is critical that the family emphasizes listening and speaking goals in their individualized plan. This emphasis on listening and speaking skills must also be continued as the child enters school.
Acknowledgements
Phonak acknowledges the permission and assistance of the following organizations for their expertise in this portion of our website:
- The Better Hearing Institute
- The Infant Hearing Guide
