Cochlear prosthesis

A cochlear implant (CI) is a surgically implanted neuroprosthetic device that provides a sense of sound to a person with moderate to profound sensorineural hearing loss. Cochlear implants bypass the normal acoustic hearing process, instead replacing it with electric signals which directly stimulate the auditory nerve. With training the brain may learn to interpret those signals as sound and speech. A cochlear implant (CI) is a surgically implanted neuroprosthetic device that provides a sense of sound to a person with moderate to profound sensorineural hearing loss. Cochlear implants bypass the normal acoustic hearing process, instead replacing it with electric signals which directly stimulate the auditory nerve. With training the brain may learn to interpret those signals as sound and speech. The implant has two main components. The outside component is generally worn behind the ear, but could also be attached to clothing, for example, in young children. This component, the sound processor, contains microphones, electronics that include DSP chips, battery, and a coil which transmits a signal to the implant across the skin. The inside component, the actual implant, has a coil to receive signals, electronics, and an array of electrodes which is placed into the cochlea, which stimulate the cochlear nerve. The surgical procedure is performed under general anesthesia. Surgical risks are minimal but can include tinnitus and dizziness. From the early days of implants in the 1970s and the 1980s, speech perception via an implant has steadily increased. Many users of modern implants gain reasonable to good hearing and speech perception skills post-implantation, especially when combined with lipreading. However, for pre-lingually Deaf children the risk of not acquiring spoken language even with an implant may be as high as 30% . One of the challenges that remain with these implants is that hearing and speech understanding skills after implantation show a wide range of variation across individual implant users. Factors such as duration and cause of hearing loss, how the implant is situated in the cochlea, the overall health of the cochlear nerve, but also individual capabilities of re-learning are considered to contribute to this variation, yet no certain predictive factors are known. Despite providing the ability for hearing and oral speech communication to children and adults with severe to profound hearing loss, there is also controversy around the devices. Much of the strongest objection to cochlear implants has come from the Deaf community. For some in the Deaf community, cochlear implants are an affront to their culture, which as some view it, is a minority threatened by the hearing majority. André Djourno and Charles Eyriès invented the original cochlear implant in 1957. This original design distributed stimulation using a single channel. Two years later they went their separate ways due to personal and professional differences. William House also invented a cochlear implant in 1961. In 1964, Blair Simmons and Robert J. White implanted a single-channel electrode in a patient's cochlea at Stanford University. However, research indicated that these single-channel cochlear implants were of limited usefulness because they can not stimulate different areas of the cochlea at different times to allow differentiation between low and mid to high frequencies as required for detecting speech. NASA engineer Adam Kissiah started working in the mid-1970s on what could become the modern cochlear implant. Kissiah used his knowledge learned while working as an electronics instrumentation engineer at NASA. This work took place over 3 years, when Kissiah would spend his lunch breaks and evenings in Kennedy’s technical library, studying the impact of engineering principles on the inner ear. In 1977, NASA helped Kissiah obtain a patent for the cochlear implant; Kissiah later sold the patent rights.