Creating the Bionic Ear: The Central Role of Cybernetics

Graeme Clark is the inventor of the cochlear implant. He was the dinner Keynote Speaker at the 2016 Conference on Norbert Wiener in the 21st Century, Melbourne, Australia, held July 13-15, 2016. These are his remarks.

Professor Iven Mareels and distinguished guests.

Tonight we celebrate the great scientific contributions of Norbert Wiener who was a pioneering researcher in stochastic and noise processes, and is considered the founder of cybernetics. He defined cybernetics as the scientific study of control and communication systems in both the animal and machine (derived by Wiener in 1948 from the Greek – κυβερνητης to steer or to govern). The study of cybernetics is important for engineering, system control, computer science, biology, neuroscience, philosophy, and the organization of society. As with many geniuses, Wiener was also very absent-minded. It was said that he returned home once to find his house empty. He inquired of a neighborhood girl the reason, and she said that the family had moved elsewhere that day. He thanked her for the information and she replied. “That’s why I stayed behind, Daddy!”

In 1967 when I set out to see if we could steer electrical stimulation of the auditory nerve past a malfunctioning inner ear and restore speech understanding for profoundly deaf people, I did not realize at the time this was entering the field of Cybernetics. In doing so I came to learn that neurophysiology and electronics were both necessary for a successful outcome.

This brings up my first challenge of developing a cochlear implant where it wasn’t good enough to bring neurophysiology and electronics together to bring help to deaf people. It was necessary to discover how patterns of neural response were perceived and then how these perceptions were consciously experienced as speech. To do this meant developing, in conjunction with the University of Melbourne’s Department of Electrical Engineering, an implantable box of electronics for multi-channel stimulation of an array of nerve fibers in the inner ear. In 1978 it was the most complex package of electronics to be surgically inserted in a patient.

Then in 1978 our most significant breakthrough occurred when we discovered that stimulating different frequency sites in the inner ear were not only perceived as pitch as occurs with sound waves, but were experienced as vowels. The vowels varied according to the site of excitation in the inner ear for the resonant frequencies of speech. The resonance depended on the shape of the oral cavity. This finding indicated that the neural connections in the brain had become arranged to decode information that was perceptually important as speech.

The discovery of a successful speech code on our first patient made it the first prosthesis to provide speech understanding for profoundly deaf people using electrical stimulation alone. This also occurred for a second patient who had been deaf many years indicating the conscious experience of speech could lie dormant through retained synaptic connections to brain cells and the enfolding of proteins in the cells. It was exciting to realize it was the first sensory-neural prosthesis to effectively bring electronic technology into a functional relationship with human consciousness.

When the prosthesis gave spoken language to young children whose brains had never been exposed to speech and was approved by the U.S.Food and Drug Administration, it became the first advance in helping profoundly deaf children to communicate in the last 250 years.

Figure 2. Clark with Rod Saunders, who was the first trial subject, with the prototype University of Melbourne receiver/stimulator, and the wearable speech processor that incorporated its initial coding strategy.

 

Figure 3. A test arrangement for Rod Saunders where relatively soon after the surgery we discovered the most important finding that led to an effective coding strategy for speech understanding. This was that timbre for frequency place of stimulation also correlated with vowel perception, and the timbre of the pitch correlated with the second formant frequency of the vowel experienced. Thus it pointed to the fact that the brain was wired for this pattern of stimulation for the perception of pitch and the conscious experience of speech. Rod perceived sounds when stimulating different frequency regions of the cochlea. Stimulating the apical end of the cochlea was perceived as dull and the vowels experienced had low second formant frequencies and stimulating the basal end of the cochlea was perceived as sharp and also experienced as vowels but with high second formant frequencies.

In addition, the success of the bionic ear also led to the creation of a new discipline which in 2003 was referred to as medical bionics. This discipline requires cross-fertilization from nanotechnology, electronics, trophic factors, stem cells, and biomaterials to achieve the best outcomes. Such a center for medical bionics could lead to 1) bionic spinal cords, as we know from recovered spinal cords there are viable cells below the injury waiting to be stimulated; 2) bionic eyes, as stimulating the retina or visual cortex could lead to enough points of light for visual acuity; 3) control over seizures, as with deep brain electrodes there is enough time to record an abnormal rhythm before reversing its effects to control epileptic seizures; and 4) drug delivery, as nanostructured interfaces for drug delivery are proving to be exciting possibilities for medical therapy.

Figure 4. This is a photo of the first two young children in the world to have the multi-channel implant in 1985 (Bryn Davey) and 1986 (Scott Smith). The exciting finding was that in spite of little exposure to sound to establish brain neural connectivity the coding situation for adults was effective for children. When approved by the U.S. Food & Drug Administration, this implant was established as the first major advance in 250 years to help profoundly deaf children communicate.

Figure 5. Marie and Paul Trainor (Owner and founder of Cochlear) with Margaret and Graeme Clark. Our industrial partner Cochlear played a fundamental role in its industrial development.

Finally, I would like to congratulate Prof. Iven Mareels, and all associated with this very successful symposium, which should realize the vision of Norbert Wiener. I hope you will take away the pressing need to do convergent research to make next generation advances for the welfare of mankind. This field is truly one where exciting innovations will occur.