The Steady Evolution of Modern Bionic Ear Technology
Although commonly referred to as a bionic ear, the product if this technology is more accurately described as a cochlear implant. As this more descriptive label implies, it is a device that is designed to be surgically implanted into the snail-like organ of the inner ear known as the cochlea. Once in position, its role is to generate electrical impulses from incoming sound signals for onward transmission to the brain via the auditory nerve. To understand how the device works it is first necessary to understand the function of this tiny pair of organs located in the innermost chambers of the ears.
External sounds are the result of vibrating molecules in air. These impinge upon the highly responsive eardrum or tympanic membrane which vibrates in response, mimicking the incoming frequencies. The vibrating membrane then transfers its energy to the first of three tiny bones that relay the vibrations to the window of the cochlea whose subsequent behaviour forms the basis of bionic ear technology. Instead of generating electrical impulses, however, the movement of the cochlear window agitates fluid within, which in turn disturbs hair-like sensory cells present on the inner lining. The response is a series of nervous impulses rather than electrical ones but these too are passed to the brain via the auditory nerve for interpretation.
Clearing, hearing is a product of both conductive and sensory activity and if either is impaired the result will be varying degrees of deafness. Amplification devices in the form of electronic hearing aids, in most instances, are sufficiently effective to compensate for conductive and sensory deafness except where the condition is more profound and it is in such cases that the product of bionic ear technology may prove to be the only viable alternative.
The race to develop a cochlear implant was probably initiated when, in the 1950s, a pair of French surgeons applied electrodes to exposed nerves in the ear and the patient reported hearing a noise rather like a cricket chirping. By 1957 the first single channel device was developed but abandoned following several failures. By 1964, the focus was on multichannel devices, each carrying an individual frequency range at which a patient’s hearing was known to be impaired. Users, however, were still unable to distinguish speech at this stage and only in 1972 did the first major breakthrough emerge and patients begin to experience the intelligible sounds needed to rehabilitate them into a predominately hearing society.
Since then bionic ear technology has progressed rapidly. The multichannel device has become the norm and, while the number of channels may vary, the individual components of these devices are common to them all. These include one or two readily-concealed microphones; a processor designed to isolate audible speech and split the incoming signal into its separate channels and a transmitter, placed behind the ear, which passes the signal to a receiver located in the bone just beneath it. The receiver converts the incoming signal into electrical impulses that are passed via a cable to an array of up to 22 individual electrodes wound through the cochlea.
Not everyone may need or is suitable for cochlear implantation. A professional evaluation by an audiologist at The Ear Institute will determine conclusively if you are a candidate for bionic ear technology.