The multiple-channel cochlear implant: the interface between sound and the central nervous system for hearing, speech, and language in deaf people—a personal perspective

Abstract

The multiple-channel cochlear implant is the first sensori-neural prosthesis to effectively and safely bring electronic technology into a direct physiological relation with the central nervous system and human consciousness, and to give speech perception to severely-profoundly deaf people and spoken language to children.Research showed that the place and temporal coding of sound frequencies could be partly replicated by multiple-channel stimulation of the auditory nerve. This required safety studies on how to prevent the effects to the cochlea of trauma, electrical stimuli, biomaterials and middle ear infection. The mechanical properties of an array and mode of stimulation for the place coding of speech frequencies were determined.A fully implantable receiver-stimulator was developed, as well as the procedures for the clinical assessment of deaf people, and the surgical placement of the device. The perception of electrically coded sounds was determined, and a speech processing strategy discovered that enabled latedeafened adults to comprehend running speech. The brain processing systems for patterns of electrical stimuli reproducing speech were elucidated. The research was developed industrially, and improvements in speech processing made through presenting additional speech frequencies by place coding. Finally, the importance of the multiple-channel cochlear implant for early deafened children was established.Keywords: multiple-channel cochlear implant; electrical stimulation of the auditory nerve; management of severe-profound hearing loss OVERVIEWThe multiple-channel cochlear implant restores useful hearing in severely-profoundly deaf people. It bypasses the malfunctioning inner ear (cochlea) and provides information to the auditory centres in the brain through electrical stimulation of the hearing (auditory) nerves (figure 1). It has enabled tens of thousands of severelyprofoundly deaf people in over 70 countries to communicate in a hearing world. Deaf people have significant limitations communicating at home and in work environments, and this substantially affects their quality of life. Children born deaf or deafened early in life have difficulty developing spoken language. This affects their education, and as a result it is harder to obtain employment. The child's deafness may also create stresses within the family. Hearing occurs normally when sound vibrations are transmitted via the external and middle ears to the sense organ of hearing (organ of Corti) in the cochlea (figure 2). The organ of Corti lies on the basilar membrane, which vibrates selectively to different sound frequencies, so that it acts as a sound filter. High frequencies produce maximal vibrations at the basal end, and low frequencies at the apical end. Inner hair cells in the organ of Corti (figure 2) convert sound vibrations into electrical impulses that provide temporal and spatial patterns of auditory nerve excitation in the higher brain centres. In most cases, when a person has a severe-profound hearing loss they will have lost most ...

Light induced stimulation and delay of cardiac activity

“…To adjust 20 or repair signaling in these systems, it is often necessary not only to provide signals to the network, but also to simultaneously record network activity. Applications for treatment of several kinds of diseases or disorders such as loss of sensory perception [1,2,3] central nervous system 25 disorders or loss of limbs [4,5,6] would all benefit from bidirectional communication with electrogenic networks of cells. Micro electrode arrays (MEAs) have been established as an electrical recording system that is non-invasive for 30 electrogenic cells [7].…”

Embedding of Internal and External Components of Cochlear Implant on to a Single Integrated Circuit

“…A study by Kim et al 8 (Busan, Korea) suggests that use of a cochlear implant in one ear also extends the window of opportunity for implantation of the second side. Paediatric unilateral cochlear implant users were given a trial with a contralateral hearing aid, and 42 subjects who did not show benefit were implanted on the second side after a mean gap of 5.5 years.…”

“…A sensor based built in microphone [8][13] which can detects and senses the various sounds available in nature. The microphone must be specifically designed for the purpose of voice communication ,and the…”

The Development of the Nucleus® Freedom™ Cochlear Implant System

“…These early studies investigated the biocompatibility of implanted components, surgical approach to the cochlea, and the safe limits for electrical stimulation. [2][3][4][5] The culmination of more than a decade of research was the prototype University of Melbourne multichannel implant, a fully implanted system with an intracochlear array of 10 electrodes that received power and data from an external speech processor system via radio frequency. Results from the 3 patients implanted in 1978 to 1979 confirmed the surgical approach and engineering design, and subjects gained some benefit from their devices when using a prototype speech processor.…”