Sunday, February 26, 2012

My experience at the Cochlear Implant Clinic

For the past 4 weeks, as part of the speech pathology degree I am currently undertaking, I spent four days a week working at the Cochlear Implant Clinic at the Royal Eye and Ear Hospital in Melbourne Victoria. It's been like working in a miracle zone. Every single day I've been astonished with delight.

The clinic is the place in Victoria and Tasmania where people come to get cochlear implants. But beyond that, they are pioneers of the cochlear implant. The implants, conceived and developed right here in Melbourne by Professor Graeme Clark and his colleagues, are now used by more than 120,000 people worldwide. The clinic does implants for both adults and children, but because I was working with the three speech pathologists at the clinic, who work almost exclusively with the children who receive implants, I was almost entirely working with children. Hence my daily astonishment and delight.

There are 3 parts to your ear--outer, middle, and inner ear. The inner ear, called the cochlea, is shaped kind of like a nautilus shell. It forms a spiral, and sound travels along that spiral, where there are ~16,000 tiny little cells called hair cells. Sounds of varying frequencies activate varying hair cells, with higher pitch sounds activating hair cells in the lower part of the spiral, and lower pitch sounds activating cells in the higher part of the spiral. When the hair cells are activated, they send signals to the auditory nerve, which in turn delivers signals to the auditory cortex of your brain, causing you to hear sound. The fact that you have 16,000 hair cells means that you get incredibly high fidelity sound quality. You hear the tiniest nuances of speech, of music, of your air conditioning, of thunder and snow falling--all the sounds that we often take for granted.

For most of history, children who were born with cochleas that didn't work simply never got to hear. Having cochleas that don't work on both the left and the right sides is called bilateral profound sensorineural hearing loss. It means that while the sound may get to your cochlea, your cochlea is unable for some reason to use the hair cells to change the sound into the elecrochemical signal that travels down your auditory nerve to your auditory cortex.

The cochlear implant consists of two parts, an internal and an external. The internal part has a tiny little tube with 22 electrodes in it. This tube is inserted into the cochlea, and the electrodes are of varying lengths and thus reach to various parts of the spiral. Each electrode, when it carries power, activates in a different of the cochlea, creating input to the auditory nerve at various frequencies. Of course there is loss of fidelity with 22 electrodes now doing the work that was previously done by 16,000 hair cells. Nevertheless, I even saw one of the children with whom I worked singing a tune! The external part of the implant contains 2 small microphones and a tiny little computer with some pretty amazing software. It takes incoming audio signal and processes it, then sends information to the internal part thusly activating the 22 electrodes in the cochlea.

Being born with both cochleas not working used to mean, for most people, being part of a very tiny first language group--sign language--with learning spoken language being incredibly difficult to impossible. Now, in Australia and many western nations, universal newborn hearing screening means that children born with little or no hearing are identified by health professionals before they leave the hospital in which they were born. And in more and more cases, this means that somewhere between the ages of 6 and 9 months they will likely receive one or two cochlear implants, and thus have access to sound from a very young age. Barring any other difficulties, they will grow up hearing and learning spoken language in pretty much the same manner as their normally hearing peers. They will be able to have conversations with any of the many native speakers of their larger community's spoken language, and will have the option to learn any other spoken language they might choose, gaining access to conversation with almost any of the 7 billion of us.

So every day I was working with little children who had received cochlear implants and who were now understanding and using spoken language at the same developmental level as their typically hearing peers. I grew up hearing this story about Jesus miraculously healing a deaf fellow. And here we are, healing the deafness of children early enough to give them access to spoken language, as a matter of course, almost. It's miracles every day. Hurrah!

P.S. I want to point out that I mean absolutely no disrespect for the deaf community. Having never really been part of a small minority group, I can't even really imagine what this sort of transitional time must be like for that community. It seems to me that it might be something like being part of a very small first language group, a few hundred people in a big city, for instance, not being able to learn a second language, and then suddenly all of the children in the community, who previously would have learned your language, are now learning the majority language and are no longer learning your language at all. I wonder if there are parallels between the current transition for the deaf community, with the advent of universal newborn hearing screening and young cochlear implantation, and the experience of other minority language groups whose language are dying because the children are assimilating and learning only the majority language. I'd be very open to hearing criticisms of my viewpoint or stories from within the deaf community. I would definitely want to respond to such stories with opennness and respect.