To understand cochlear implants it’s important to remember how the ear works. The ear is divided into three parts: the outer ear, the middle ear, and the inner ear. Sound waves traveling down the ear canal cause the eardrum to move, which makes the bones of the middle ear vibrate. Those vibrations stimulate the hair cells of the cochlea, a pea-sized, spiral-shaped structure deep in the inner ear. The cochlea sends signals to the auditory nerve which are transmitted to the brain where sounds are interpreted.
Most cochlear implant candidates have normal outer and middle ear function. But when their inner ear fluids are stimulated, the hair cells of the cochlea do not respond or have such a limited response that electrical signals are prevented from reaching the brain. People who benefit from hearing aids have enough of a response that a signal does get through. For them, hearing aids help by amplifying incoming sounds.
A cochlear implant provides a detour around the hair cells. The implant contains a number of parts, including an array of electrodes implanted in the cochlea. Those electrodes stimulate the auditory nerve fibers directly, from within the inner ear. As shown below, incoming sounds are picked up by a microphone which delivers them to a speech processor, a small computer analyzes the incoming sounds and converts them to an electrical code. The coded electrical signals travel from the speech processor to a transmitting coil, across the skin, to an implanted receiver where the electrical signals are delivered from the auditory nerve to the brain.
The first generation of implants was capable of delivering only a limited amount of auditory information. Current models have multiple channels and electrodes that allow users to perceive a much broader range and complexity of sounds, including speech.
To hear speech and music as they would be heard by someone wearing a cochlear implant, visit: https://www.youtube.com/watch?v=1dhTWVMcpC4
Courtesy of Cochlear Americas
”Technology is wonderful, but you have to have the people – the audiologist, the speech pathologist, the auditory trainers – working with the patient… There’s still a human being involved and every single person is unique; what they need can not always just be solved by a piece of equipment. There needs to be the professional component that’s added”
-Stephanie Sjoblad, AuD, Assistant Professor and Clinical Coordinator, Division of Speech and Hearing Sciences
Courtesy of Stephanie Sjoblad
For nearly 40 years, I have lived the same lives as my patients. I was diagnosed at age 5 with a mild to moderate hearing loss, and I began to wear a hearing aid in the first grade. Fortunately by then, I had already begun to develop language skills. However, each year my hearing got progressively worse. I was a good student, but worked so hard to learn the material. In college I had two hearing aids, note takers, and a front row seat to help me hear the lectures. Although I wore good hearing aids, I was not aware of additional technology that could have helped me hear more easily. I was thirty years old before an audiologist introduced me to FM technology. It was an amazing experience at the time, but at the same time very frustrating that no one had told me about this technology sooner, as communication would have been so much easier for me.
”We need more people like you in this field – who understand what it’s like to be on the other side of the testing booth.”
I wanted to go into the field of audiology to help people with hearing loss, but found it very difficult to break into the field. I was discouraged by others as they did not think I could be successful in clinical settings. The response to my inquiries was ”How could a hard of hearing, almost deaf person, be an audiologist?’ Jackson Roush, the UNC Division of Speech and Hearing Sciences Director, had a difference of opinion. He believed that someone with hearing loss could be a great contributor to the profession and that audiology was more than just knowing how to diagnosis hearing loss. It is about understanding the patient needs and helping finding solutions. I earned a Master’s degree in Audiology at UNC. I then worked in the private sector for two years while earning my AuD degree. During this time, my hearing loss continued to decline, but fortunately hearing aid and FM technology got better. However, by the birth of my second child, I was considered profoundly deaf. Now, after years of lip-reading, being fitted and re-fitted for hearing aids, and no longer being able to communicate by phone, I decided it was time for me to get a cochlear implant.
Stephanie Sjoblad discusses her own experience with hearing loss and getting a cochlear implant; Kathryn Wilson, MA, Assistant Professor, Division of Speech and Hearing Sciences, discusses her therapy work with Stephanie Sjoblad after the cochlear implant.
In April of 2009, I had cochlear implant surgery at UNC Hospitals by Dr. Craig Buchman. It was a 90-minute surgery and I went home the same day. My bandage was removed after five days. When the implant is activated, people have reported the sound is very robotic and unnatural. It is also usually very unusual for one to understand speech. However, during my cochlear implant activation, I was able to understand complete sentences. Someone asked, ”What are we having for dinner tonight?” and I could understand without having to look at the person speaking. I knew then my life was only going to get better.
“What are we having for dinner tonight?”
Speech-language pathologists, Kathryn Wilson and Melody Harrison, worked with me on focusing and listening to specific sounds, recognizing stereotypic phrases, talking on the phone, listening to familiar voices, and listening to strangers’ voices. Therapists can identify problems and teach parents and family to recognize signs such as speech changes, the need to repeat, inability to hear at a distance, or a need for face/visual cues. These can be red flags that help target therapy and identify problems early.
“Now with my 2.5-year-old there are days I’ll quickly pop my hearing aid in first thing in the morning and I will have no idea what he is saying. But at the moment I put on my implant, his speech turns into words.”
As an audiologist with hearing loss, I now know there are lots of solutions for people with hearing loss. I believe communication is vital to enjoying life. I am grateful not only for technology, but for the speech and hearing professionals who have impacted my life and enjoy the opportunity to help shape the next generation of audiologists as a faculty member at UNC. I encourage people who are not sure if hearing aids or an FM system or even a cochlear implant would benefit them to find an audiologist to learn more.
Listen to demos of what speech and music sound like through a cochlear implant: https://www.youtube.com/watch?v=1kQPZdQxDbo