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Research and development process
Initial research
Inspiration
Resolving problems
Distribution clinics, an innovation too
Developing a prototype of the cochlear implant
Finding the first patients


Cochlear - MAIN

Initial research
As a PhD student at the University of Sydney in 1967 Graeme Clark began to review the available research to "investigate whether a single or multiple-channel (electrode) cochlear implant would be possible for the management of a profound hearing loss." (Clark, 1969: 1)

Since 1970 he has led the research in the Department of Otolaryngology at the University of Melbourne that has resulted in a multiple-channel cochlear implant that can provide significant understanding of speech for severely and profoundly deaf children and adults.

Inspiration
When Australian otolaryngologist Graeme Clark began developing the cochlear implant or as it was more commonly known — the bionic ear — overseas researchers used an implanted device that had wires leading from the inside to the outside of the head. According to Clark this presented too many opportunities for infection. He believed that the implant should be totally imbedded and receive information via radio signals rather than linked to an external source. Other researchers also had different ideas about where the electrode should be placed. Some placed it outside the cochlea, others directly onto the auditory nerve.

Clark believed that the electrode should be placed into the cochlea but could not work out how to get the electrode inside the tiny spiral without opening it up. He was inspired by nature to find the solution. When at the beach he picked up a seashell that resembled the shape of the cochlea. Nearby was a clump of wild grass that he pulled a few blades from. As he twined the blades through his fingers he noticed that they changed stiffness along their length and were tapered at the top. Looking at these things he had the idea of carefully inserting the blade of grass into the shell until it went almost completely into the spiral. After this he imagined a bundle of electrodes of fine, strong and flexible wire that could be inserted into the human cochlea by easing around the corners and positioned to correctly stimulate nerve endings.
snail

Electrode
Electrode stimulation pattern resulting from sound 'ah' (Cochlear Pty Ltd)


Resolving problems
Ethics
Based on the research he had conducted for his PhD, Graeme Clark and his research team at the University of Melbourne began fine tuning the design of the implant. Using Clark's inspiration of the shell and blade of grass they began to explore the notion of an electrode array.

As the
…whole project was still in the research stage, the Australian team determined to follow the ethical recommendations made at the Declaration of Helsinki in 1964 for guiding doctors in clinical research, as well as the recommendations in the Statement of Human Experimentation published by the National Health and Medical Research Council of Australia in 1976. (Epstein, 1989: 44)

As animal experimentation was needed before the implants could be used on humans there were also animal ethics to consider.

For more information on animal ethics:
Animal Ethics Committees Manual of Policy and Procedures, The University of Melbourne, March 1996

Technical considerations
Some of the problems the research team had to overcome included:

  • the electrode bundle had to be precisely manufactured
  • the materials needed to be resistant to body fluids and harmless to the recipient. Clark and his team used Teflon® coated platinum wires as electrodes to fit in the cochlea. The multi-electrode array successfully passed into the cochlea. To resolve the problem of finding materials resistant to body fluids the designers looked to work being done on the pacemaker implant. It was originally cast in epoxy resin, however the cochlear implant researchers believed a metal may offer lightness and body fluid resistance. Pure titanium was trialled for the casing by G. A. and L. Harrington.
    G. A. and L. Harrington was the first company to "deep draw titanium in Australia. In this process which requires special expertise, sheet metal is turned into the required shape with a high depth to width ratio." (Epstein, 1989: 48)
  • the feedthrough wires had to be insulated - high alumina ceramic was selected. The Ceramic Corporation Pty Ltd, specialists in precision industrial ceramics were approached. The owner, Miroslav (Mirek) Kratochvil emigrated to Australia as a political refugee from Czechoslovakia, developed a new ceramic which was fired at a much higher temperature than normal to give the properties needed.
  • welding the parts together. A new alloy was developed and trialed. These three components ensured
    …a hermetically sealed implant, completely resistant to body fluids. …These discoveries were to have an enormous influence on the development of the Australian bionic ear, for the electronics to be used in the implant would also need the protection which only the hermetic seal devised for the pacemaker could give. (Epstein, 1989: 49)
  • tests had to be done to determine how to best reach the cochlea in surgery.
  • clinical trials and selection of suitable recipients had to be carried out. These trials have influenced current procedures as well. An effective service network was an essential ingredient to ensure that the innovation would fulfil a user's needs.
  • the implant would need to last a long time — a design life of 70 years.

Funding the research
Funds were needed to continue the project. Funding was donated by Melbourne Apex Club, a telethon organised by Sir Reginald Ansett and Channel 0, The National Health and Medical Research Council and Lions Clubs International and at a later stage the Deafness Foundation of Victoria.

Distribution clinics, an innovation too
The success of the Cochlear implant is founded on a world wide network of dedicated clinics. At these clinics, the Cochlear implant is implanted by a surgeon. More importantly, each recipient is trained by an audiologist to recognise speech using the system. Training is needed to recognise the unfamiliar sounds generated by the speech processor. Try to recognise the nursery rhyme in this simulation of processed speech.

Each system is customised to suit the individual and fine-tuned to convey the maximum amount of speech information. Regular repeat visits ensure that the system is operating at its peak.

The success of the Cochlear implant system rests on careful selection of appropriate patients, reliable technology, and a network of clinics staffed by highly skilled surgeons and audiologists.

testing
(Cochlear Pty Ltd)

Developing a prototype of the cochlear implant
The receiver-stimulator in the prototype device needed

…the equivalent of 6000 radio valves to make it work, a sheer impossibility until the development of integrated circuit technology when that same amount of electronic circuitry could be condensed into a tiny microchip. (Epstein, 1989: 43)

The receiver-stimulator was designed and manufactured by Melbourne University's Department of Electrical Engineering and Department of Otolaryngology.

A prototype receiver-stimulator with a connector for 10 channel electrodes, all to be implanted, and the University of Melbourne was able to lodge an application for patent rights. The device was called Umdolee (University of Melbourne Departments of Otolaryngology and Electrical Engineering).

The gold box multiple electrode device measured 4.2 x 3.2 x 0.85 to 1.3cm. It included a sandwich of three razor-thin substrata and the thousands of transistors. The electrodes themselves consisted of a bundle of twenty fine wires, each insulated and fine as a human hair, the diameter of the whole bundle being about 0.5 mm. This bundle had to replace the work of some 20 000 to 30 000 nerve fibres in the normal ear and transmit sound impulses to the brain. …each pair of electrodes controlling a sound of a different pitch. (Epstein, 1989: 43)

The speech processor, however, had not been developed. This was the device to break speech into meaningful signals that the brain could recognise. The strategies to teach someone how to recognise speech could only be developed when a person who had received an implant worked with engineers and audiologists.

Finding the first patients
To ensure testing was rigorous and accountable, assessments for selection of patients and monitoring implantees was carried out in a multidisciplinary centre featuring specialists in:

  • phonetics: the study of speech sounds and their production
  • audiology: the diagnosis and rehabilitation of hearing loss
  • auditory physiology: the physiology underlying normal and impaired hearing, speech and language in humans. Physiological measurement techniques are used to identify and assess hearing impairment.
  • information science: the collection, organisation and analysis of data.
  • otology: the diagnosis and treatment of disorders of the ear.
  • psychophysics: how electrical stimulation by the cochlear implant is received by the user and how best to present speech information to them.
  • psychology: patient support and family counselling.
  • psychoacoustics: conducts basic and applied hearing research specifically aimed at understanding and correcting impaired hearing.
  • speech rehabilitation: re-establish speech patterns.
  • electrical engineering support: identify and modify hardware and software problems.

Once the prototype was developed and extensive animal testing proved satisfactory the device was ready for implanting in a human. Rod Saunders received a ten channel implantable device in 1978. The surgery was a success and Rod heard his wife speaking to him after the device was turned on.

For a more detailed history of the cochlear implant:
http://www.medoto.unimelb.edu.au/info/history2.htm
and for a History of the University of Melbourne/Cochlear Limited Cochlear Implant
http://www.medoto.unimelb.edu.au/info/history3.htm


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