cochlear implant: Research, development and commercialization
Univ. Doz. Dipl.-Ing. Dr. techn. Dr. med. h.c. Ingeborg J. Hochmair-Desoyer and em. o. Univ. Prof. Dipl-.Ing. Dr. techn. Dr. med. h.c Erwin Hochmair
For the development and commercialization of the world’s first multi-channel microelectronic cochlear implant.
Prof. Blake S. Wilson, Ph.D., D.Sc., D.Eng., Dr. med. h.c. (mult.)
For research and development of an auditory coding strategy for cochlear Implants named “Continuous Interleaved Sampling” (CIS) in the late 1980’s, which has dramatically improved speech recognition without visual cues in these patients.
Development of a multichannel cochlear implant and a proper coding strategy to enable speech recognition
Anatomically, the human ear consists of three major parts, namely the outer ear, the middle ear
and the inner ear. While the outer ear mainly collects the acoustic pressure waves from the
environment and the middle ear transforms the sound from air-based to liquid-based, the most
important subfunction of hearing is located in the inner air. In fact, it is here where acoustic
pressure signals are transformed to electrical signals in nerve cells. To allow this transformation,
the auditory nerve connects to an anatomical structure named the cochlea.
Inside this helical structure, the so called hair cells, in conjunction with the basilar membrane,
translate mechanical information into neural information. If these cells are damaged, the acoustic
information can not be transmitted to the brain anymore, resulting in hearing impairment.
For a long time, deafness was believed to be a disease which could only be cured by a miracle.
Hence, the introduction of an electronic device re-installing hearing certainly was a break-through
in the therapy of deafness. The main idea of such a cochlear prosthesis is therefore to bypass the
normal hearing mechanism (outer, middle, and part of the inner ear including the hair cells) and
to electrically stimulate the remaining auditory neurons directly. For this, the device needs a
microphone to collect acoustic information from the outer world, an electronic signal processor
and a direct electrical connection to the auditory nerve cells. As a permanent connection to
the auditory nerve would create infection after some time, parts of the device need to be
implanted which requires an additional signal transmission link from the outer electronics to the
Based on research starting in the 1950s, single-channel implants were first implanted in human
subjects in the early 1970s. At the time, the still rather premature coding strategies did allow to
preserve periodicity of the acoustic signal. However, temporal details in the speech signal were
distorted or discarded. In most patients, these devices did not allow speech recognition without
lip reading and sign articulation. To overcome these limitations, multichannel implants were
introduced in the late 1970s. These more advanced devices provided electrical stimulation at
multiple sites in the cochlea by using an array of electrodes.
Multichannel cochlear implants, in connection with the increase in electronic miniaturization
and proper coding strategies, formed the basis for the modern therapeutic success rates resulting
in proper speech recognition without direct sight contact for many patients. At the time, the
digital Continuous Interleaved Sampling (CIS) approach proved to be superior to other analogue
techniques like Compressed Analogue (CA). In fact, CIS enabled dramatic improvements in
speech recognition. With this new coding strategy, many patients were suddenly able to again
communicate via the telephone.
Our winners of this year´s technology award were true pioneers in this development. Two of
the winners, the Hochmairs, were the first to scientifically describe multichannel electrode arrays
and introduce them to the market. The first implantation of a multichannel cochlear implant was
performed in Vienna in 1977 and used their design. Consequently, Blake Wilson’s research
and development of the auditory coding strategy Continuous Interleaved Sampling (CIS) in the
late 1980’s used the opportunities provided by this new hardware and vastly improved the overall
therapeutic performance that was in place at the time.
Univ.-Prof. Dr.-Ing. Dr. med. Steffen Leonhardt