ĎIíve had a cochlea implant. I know what sound is. I know what speech is. So why canít I hear straight away? And how can I explain this to my family and friends?í For those of us whoíve gone deaf and had a cochlea implant these are questions we hear all the time.
So first things first. Why canít you hear and understand speech straight away? Well truth be told, some people can but even those who can, report that the sound is funny. (A chipmunk underwater, Donald Duck, metallic sounding, musak are some of the words used by people to describe it).
When you go deaf with a sensorineural hearing loss, the 15,000+ tiny hairs in your cochlea die away. These hairs vibrate with the sounds you hear Ė in your environment and in speech Ė and these vibrations are changed by the hairs into an electrical signal that then stimulates your hearing nerve. The hearing nerve takes the signal to the part in your brain where you interpret sound. In effect the hairs are a connection between the hearing anatomy and your hearing nerve. So if these hairs are not there then it doesnít matter how loud the sound is you will never hear it because the connection is missing.
When you have a cochlea implant the speech processor converts sound vibrations into electrical impulses and conducts it via the electrodes into your cochlea and directly stimulates your hearing nerve, by-passing the damaged hair cells.
For most of us who have been deaf for a long time our hearing nerve hasnít been stimulated for many years. Youíve all probably heard Ďuse it or lose ití. We know that if something in our body isnít used then our muscles and nerves atrophy. When someone is bed ridden for even a few weeks they can have difficulty walking and using those muscles will even hurt.
Our hearing nerve is just the same and itís a bit of a shock for it to start getting stimulation again. This is one reason why the sound is funny even if we can understand speech when we are first switched on. The hearing nerve is waking up and only part of it can carry the sound. But there is an even more important reason. There are neurons from our hearing nerve to the part of the brain where we hear and these neurons die away from lack of use. So at first, even though we are now getting stimulation it canít get through very well and wonít be interpreted by us because some of the neurons are weak or missing altogether. Amazingly, our brains have a high level of plasticity and with continued stimulation our brain forms new neural pathways. So the more we stimulate our hearing sense the more likely we are to stimulate growth of these pathways. This is why so many cochlea implantees report that speech improves, music sounds better over time and they start to better understand their environmental sounds.
Unfortunately, many of us have family and friends who expect that a cochlea implant is a miracle cure. They think we are getting sound so of course we should now understand it perfectly. In fact, many of us, while having had expectations of a cochlea implant explained very carefully by professionals, still donít get it and expect to hear immediately too.
When I had my first implant 8 years ago I had lost the experience of sound. I really couldnít get in touch with what it felt like to be hearing. But I still hoped that everything would be normal at switch on. Of course it wasnít. Although I understood speech in a few minutes without the need for lip reading (and my score without lip reading was 0% in both ears prior to implant) it still sounded awful. I was extremely disappointed and that day wished I hadnít had the implant. But as my brain became used to the stimulation and with further mappings over the next few weeks sound started to sound the way I remembered and I got back the ability to listen to the radio, have conversations in the dark and use a phone.
But my second implant, even though in the ear which had hearing for longer, was a different story. It took a couple of weeks before I understood speech and even a year later the sound is still distorted although I can understand it without lip reading. But it improves and each time I have a map we tweek it a little more and it improves even more.
Even with one ear not working as well as the other, together, I have better hearing and understanding than I have had since I was about 25 years old (35 years!)
So to everyone who has had or is contemplating a cochlea implant Ė they do work. They can work immediately but for others it takes time Ėeven for the same person. Donít give up. Work at it. If you canít stand the high frequencies, then keep them low and slowly increase them. (This is my problem in my 2nd implanted ear). In time, even years, it will improve and it is just so well worth it.