Cochlear implants (CI) can free them from this isolation. They can help where conventional hearing devices have little or no effect. The origins of cochlear implants, which were developed in the 1950s and 1960s and launched on the market in 1972, date back to the dawn of the 19th century. Back then, the famous Italian physicist Alessandro Conte di Volta invented the “voltaic pile,” a forerunner of our electrochemical battery. During one of his first experiments, he stuck the two electrodes into his ears and, thus closing the circuit, he heard a buzzing or humming. However, there was no way Volta could have known that he had thus laid the foundation for the development of the modern hearing aid of the cochlear implant.

In healthy people, the acoustic stimulus of the sound waves that enter the inner ear through the auditory canal and eardrum are transformed into an electrical signal that activates the auditory nerve by means of the movement of the fine hair cells in the cochlea. We can more or less compare the function of the cochlea with that of a microphone. As the hair cells’ minute motor units are absent or stunted in people who suffer from severe hearing loss or deafness, they cannot receive, transform and forward sounds to the auditory cortex of the brain. The cochlear implant can take over this task of the cochlea to some extent. In contrast to hearing devices that simply amplify sound, the electrodes implanted in the cochlea replace the hair cells that process the signals: In electrically stimulating the auditory nerve, they enable acoustic perception. A cochlear implant es - sentially consists of two components: the actual implant, which is inserted in the cranial bone behind the ear in a surgical operation under general anesthetic, and the speech processor with a transmitter coil. The latter is worn behind the ear like a common hearing instrument.

The speech processor receives sound waves through a micro phone. With the help of its mini computer, it adapts them to the electrical sensitivity and receptiveness of the auditory nerve of the respective patient and forwards the adapted electrical impulses to the transmitter coil via a wire. The coil then transmits them wirelessly to the im - plant and its electrodes. The magnet of the implant body, which is located directly under the transmitter coil in the cranial bone, holds the coil – a small circular disk with a diameter of approximately 2.5 cm – in place on the scalp. The implant body receives the impulses from the coil through its electronic system and forwards them to the auditory nerve via the electrodes previously implanted in the cochlea by surgery. Modern implants contain 12 to 22 electrodes. Compared to the 3,000 hair cells stimulating the auditory nerve in a healthy inner ear, the acoustic stimulus triggered by a cochlear implant can, of course, only achieve a reduced sound pattern when transforming the acoustic signal. A cochlear implant may be required if a patient with a hearing device can understand no more than 40% of the words correctly in a hearing test involving monosyllabic words at a sound level of 65 decibels. The cochlear implant is an option for patients of all ages, ranging from those who were born deaf and children who lost their sense of hearing at a very young age to adults who became deaf at a later age or suffer from severe hearing loss in both ears. Deaf children should be provided with cochlear implants as early as possible – ideally at the age of one or two – as the development of their auditory pathways as well as the learning and further development of language are dependent on early acoustic impressions (speech, noises, sounds and tones) that should be as mani - fold as possible. Health insurance schemes cover the full cost of the implantation in both ears.