In this blog post, we will look at how a cochlear implant helps people who have lost their hearing to regain their hearing, and examine its principles and limitations.
What should you do if your tire is flat? The answer is simple: you should fill it up with air. If you have a problem such as a punctured tire and you cannot fill it up, you can buy a new tire and replace it. It may be a little troublesome and expensive to replace the tire, but this may be the final solution. But what if you have poor hearing? This is a little more complicated. Of course, you can wear a hearing aid in your ear to make it easier to hear. Hearing aids are a simple yet effective solution for many people with hearing loss. But what if you can’t hear well even with a hearing aid? It’s just as simple. Replace your ear!
Hearing sound means that the vibration that originated from the sound source is transmitted to the vibration of the medium, which causes the outer and middle ear to vibrate. This causes the vibration of the medium and the small hair cells of the inner ear. This is the process by which the auditory nerve is stimulated and electrical signals are transmitted to the auditory center. At this point, if there is an abnormality in any part of the process, from the outer ear, which is the entrance through which sound enters the body, to the brain that interprets the sound, there will be a problem with hearing. There are many causes of hearing loss. “Pure tone hearing loss” occurs when there is a problem with the outer ear or middle ear, which prevents the physical transmission of sound waves. In this case, you can wear a hearing aid to amplify the sound. However, amplifying sound does not solve all hearing loss. Hearing aids only increase the volume of sound, but they do not address the sensory elements necessary for recognizing sound.
On the other hand, when problems arise in the hair cells inside the cochlea and the physical signals cannot be transmitted to the auditory nerve, it is called sensorineural hearing loss. In this case, hearing aids alone are not enough to solve the problem. Hearing aids use a method that takes in sound, converts it into a digital signal, amplifies it, and then transmits it as sound waves again. This method simply amplifies the sound. Therefore, it is ineffective for patients with sensorineural hearing loss, who have difficulty accepting sound stimulation itself. In their case, they need the ability to hear the sound itself, not just increase the volume.
A cochlear implant is a device that is inserted into the inner ear through surgery to replace the damaged hair cells with a device that converts sound waves into electrical signals, just as a flat tire is replaced with a normal tire. Cochlear implants are divided into two main parts: the sound processor, which is worn externally, and the implant, which is inserted inside the body. First, when the sound reaches the external microphone, it receives an analog signal, which is then converted into a digital signal by the sound processor. This signal is then transmitted to the implant inserted in the cochlea via a coil. The implant then converts the digital signal into an electrical stimulation signal, which is then output as an electrical stimulus by the electrode. This electrical stimulation directly stimulates the auditory nerve, enabling patients with hearing loss to hear sounds at a normal level. As it directly stimulates the auditory nerve, cochlear implants can provide a solution for all cases of hearing loss, except those caused by abnormalities in the auditory nerve or auditory center.
However, cochlear implants are not a perfect solution either. First, unlike hearing aids, which can be used simply by wearing them, cochlear implants require a separate surgery to insert an implant into the cochlea. The surgery is not suitable for all patients, and a certain recovery and rehabilitation process is required after the surgery. In particular, training to acquire a new auditory experience is essential after cochlear implant surgery. In addition, the cable that connects the implant to the external sound processor must be inserted into the body. Therefore, there is a possibility of side effects from the surgery. Furthermore, although cochlear implant surgery is intended for patients with little residual hearing, the implant procedure removes any remaining hair cells, permanently causing the patient to lose their residual hearing. As a result, a cochlear implant is not suitable for all people with hearing loss.
Finally, the sound delivered to a person through a cochlear implant does not exactly match the sound that the person actually hears. This means that the cochlear implant’s final conversion of sound waves into electrical impulses and the human auditory system’s final conversion of sound waves into electrical impulses do not match perfectly. Because of this, patients who have undergone cochlear implant surgery must learn a new way to accept auditory stimulation through the cochlear implant, and a rehabilitation training process is required accordingly. Hearing training can take time, and the quality of the sounds that can be heard may vary depending on the degree of training.
Therefore, the ultimate goal of cochlear implants is to make the sounds heard through the implant and the sounds heard through the normal ear the same. Research is continuing in various areas, including the signal transmission process between the hair cells and the auditory nerve, the form of the final stimulus received by the auditory nerve, and the technology for creating artificial stimuli. Although the performance of cochlear implants has improved significantly in recent years, there is still much room for improvement. This is because the human auditory system is very complex and it is not easy to perfectly mimic its complex processes. However, thanks to these efforts, creating a perfect spare ear will no longer be a pipe dream.
When you are unable to get the sound information you want, such as a broken speaker or earphone, or a video that is not synced, you will realize the importance of sound. Cochlear implants are a technology that will give hearing loss patients a new ear in a world where they are unintentionally muted, and it will be a beacon of hope that breaks the silence that seems to last forever for them.
