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Graeme Milbourne Clark AC (born 16 August 1935) [1] is an Australian Professor of Otolaryngology at the University of Melbourne. [2] Worked in ENT surgery, electronics and speech science contributed towards the development of the multiple-channel cochlear implant. [3] [4] [5] His invention was later marketed by Cochlear Limited. [6]
Clark was born in Camden, New South Wales, to parents Colin and Dorothy Clark. He has one younger sister. [7] Clark was educated at The Scots College and studied medicine at Sydney University. [8]
He specialized in ear, nose and throat surgery at the Royal National Throat, Nose and Ear Hospital and obtained a fellowship in 1964 from the Royal College of Surgeons, London. Clark returned to Australia where he became a Fellow of the Royal Australian College of Surgeons and in 1969 completed his PhD at the University of Sydney on "Middle Ear & Neural Mechanisms in Hearing and in the Management of Deafness". [9] [10] At the same time, he completed a Master of Surgery thesis on "The Principles of the Structural Support of the Nose and its Application to Nasal and Septal Surgery".
In 1976, he returned to England to study at the University of Keele and learn more about speech science.
Clark hypothesized that hearing, particularly for speech, might be reproduced in people with deafness if the damaged or underdeveloped ear were bypassed, and the auditory nerve electrically stimulated to reproduce the coding of sound. His initial doctoral research at the University of Sydney investigated the effect of the rate of electrical stimulation on single cells and groups of cells in the auditory brain-stem response, the center where frequency discrimination is first decoded.[ citation needed ]
Clark's research demonstrated that an electrode bundle with 'graded stiffness' would pass without injury around the tightening spiral of the cochlea to the speech frequency region. Until this time he had difficulty identifying a way to place the electrode bundle in the cochlea without causing any damage. He achieved a breakthrough during a vacation at the beach; he conceptualized using a seashell to replicate the human cochlea, and grass blades (which were flexible at the tip and gradually increasing in stiffness) to represent the electrodes. [11]
Clark showed[ clarification needed ] that the electrode bundle had to be free-fitting, and the wires needed to be terminated with circumferential bands to reduce friction against the outer wall of the cochlea; as to make it[ clarification needed ] easier to pass the required distance. The bands had to be wide enough to minimize the charge density of the electric current for safety, but narrow enough for localized stimulation of the nerve fibers for the place coding of frequency.[ vague ] In order to address issues about the safety of the device, Clark conducted experiments to show that there was minimal risk of meningitis from a middle ear infection if a fibrous tissue sheath grew around the electrode bundle. The sheath was developed from a connective tissue graft from the person's own body that was placed around the electrode bundle where it entered the cochlea.[ citation needed ]
The first cochlear implant was invented and developed by Dr. William F. House. [12] House's device was a single electrode configuration, compared to the multiple electrode device developed by Clark.
Clark's first multi-channel cochlear implant operation was done at the Royal Victorian Eye and Ear Hospital in 1978 by Clark and Dr. Brian Pyman. [13] The first person to receive the implant was Rod Saunders who had lost his hearing aged 46. [14] Less than one year later, a second patient was implanted. George Watson, an Australian World War II veteran, had lost his hearing after a bomb blast thirteen years earlier. An audiologist working on Clark's team at the time described the team's first two patients as, "guys who'd put up with anything and continue to keep coming in and support the work.". [15]
After successfully completing the surgery in 1978, with his post-doctoral colleague, Yit Chow Tong, Clark discovered how multi-channel electrical stimulation of the brain could reproduce frequency and intensity as pitch and loudness in severely-to-profoundly deaf adults who originally had hearing before going deaf. Electrical stimulation at low rates (50 pulses/sec) was perceived as a pitch of the same frequency, but at rates above 200 pulses/sec, what was heard was poorly discriminated and a much higher pitch.[ citation needed ] This discovery established that the timing of electrical stimuli was important for low pitch when this had been difficult to determine with sound.[ vague ] But discrimination of pitch up to 4000 Hz is required for speech understanding, so Clark emphasized early in the development of his cochlear implant that "place coding through multi-channel stimulation" would have to be used for the important mid-to-high speech frequencies.[ citation needed ] Clark and Tong next discovered that place of stimulation was experienced as timbre, but without a strong pitch sensation. The patient could identify separate sensations according to the site of stimulation in the cochlea.[ citation needed ]
At the end of 1978, Clark and Tong made the discovery that the speech processing strategy coded the second formant[ clarification needed ] as place of stimulation along the cochlear array, the amplitude of the second formant as current level, and the voicing frequency as pulse rate across the formant channels.[ citation needed ]
in December 1978, Clark arranged that his audiologist present open-set words to his first patient, who was able to identify several correctly.
As a result, Clark went on to operate on a second patient who had been deaf for 17 years. He was able to show that the speech coding strategy was not unique to one person's brain response patterns, and that the memory for speech sounds could persist for many years after the person became deaf.
In 1982 Clark supervised the initial clinical studies mandated by the Food and Drug Administration (FDA) and in 1985, after a world trial, the FDA granted approval for his multi-channel cochlear implant for adults 18 and over who had hearing before going deaf.[ citation needed ] It thus became the first multi-channel cochlear system to be approved as safe and effective by any health regulatory body for giving speech understanding, both with lip reading and for electrical stimulation alone in people who had hearing before going deaf.[ citation needed ] After a detailed analysis of results the FDA announced in 1990 that the 22-channel cochlear implant was safe and effective for deaf children from two to 17 years of age in understanding speech both with and without lip-reading. [16]
From 1985 to 1990 Clark and the members of his Cochlear Implant Clinic at the Eye and Ear Hospital in Melbourne, followed by other clinics worldwide, found that the formant extraction speech coding strategies developed by Clark and team resulted in up to 60% of children being able to understand significant numbers of words and sentences with electrical stimulation alone without help from lipreading.[ citation needed ] With a strategy that also extracted a band of high frequencies there were increased numbers of children with improved speech perception, speech production and language scores.[ citation needed ]
In 1970 Clark was appointed as the Foundation Professor of Otolaryngology (Ear, Nose, and Throat Surgery) at the University of Melbourne, and then in 2000 he was made one of the first Laureate Professors at the University for his international recognition of scientific achievement.[ citation needed ] He held this position until he retired in 2004. He led cochlear implant research while Head of the Department of Otolaryngology.[ citation needed ] His research was funded initially by an appeal through a Telethon, and then a Public Interest Grant from the Australian government. His ongoing research to understand the functioning and improve the cochlear implant was through his grants from the National Health and Medical Research Council of Australia, the Australian Research Council, The US National Institutes of Health, and The Cooperative Research Center program. [ citation needed ] In 1983 the Bionic Ear Institute was founded by Clark, as an independent, non-profit, medical research organization. [17] The goal of the Bionic Ear Institute was, "to give deaf children and adults the opportunity to participate as fully as possible in the hearing world and to find new ways to restore brain function". The Bionic Ear Institute renamed itself the Bionics Institute in 2011 due to an expansion of its aims to not just improve the bionic ear, but to develop a bionic eye and devices capable of deep brain stimulation.
In 2002 The Graeme Clark Cochlear Scholarship Foundation was established in honor of Graeme Clark for his lifelong commitment to finding a solution for people with hearing loss, and his pioneering work in the field of cochlear implant technology. [18] Awarded by Cochlear Limited, scholarships are presented to cochlear implant recipients around the world to help defray the costs of their higher education, consisting of financial assistance towards a college degree at an accredited university for up to four years.[ citation needed ]
In recognition of Clark's contributions to the welfare of deaf people, The Graeme Clark Charitable Foundation, a charitable foundation has been established to firstly enable individuals with deafness and other sensory disorders develop their potential through appropriate biomedical, technological and educational measures.[ citation needed ]
Clark has been painted by Peter Wegner, three of these works are in the National Portrait Gallery (Australia), as an etching, [26] profile, [27] and portrait. [28]
A cochlear implant (CI) is a surgically implanted neuroprosthesis that provides a person who has moderate-to-profound sensorineural hearing loss with sound perception. With the help of therapy, cochlear implants may allow for improved speech understanding in both quiet and noisy environments. A CI bypasses acoustic hearing by direct electrical stimulation of the auditory nerve. Through everyday listening and auditory training, cochlear implants allow both children and adults to learn to interpret those signals as speech and sound.
Unilateral hearing loss (UHL) is a type of hearing impairment where there is normal hearing in one ear and impaired hearing in the other ear.
Presbycusis, or age-related hearing loss, is the cumulative effect of aging on hearing. It is a progressive and irreversible bilateral symmetrical age-related sensorineural hearing loss resulting from degeneration of the cochlea or associated structures of the inner ear or auditory nerves. The hearing loss is most marked at higher frequencies. Hearing loss that accumulates with age but is caused by factors other than normal aging is not presbycusis, although differentiating the individual effects of distinct causes of hearing loss can be difficult.
Neuroprosthetics is a discipline related to neuroscience and biomedical engineering concerned with developing neural prostheses. They are sometimes contrasted with a brain–computer interface, which connects the brain to a computer rather than a device meant to replace missing biological functionality.
The Greenwood function correlates the position of the hair cells in the inner ear to the frequencies that stimulate their corresponding auditory neurons. Empirically derived in 1961 by Donald D. Greenwood, the relationship has shown to be constant throughout mammalian species when scaled to the appropriate cochlear spiral lengths and audible frequency ranges. Moreover, the Greenwood function provides the mathematical basis for cochlear implant surgical electrode array placement within the cochlea.
The auditory brainstem response (ABR), also called brainstem evoked response audiometry (BERA), is an auditory evoked potential extracted from ongoing electrical activity in the brain and recorded via electrodes placed on the scalp. The measured recording is a series of six to seven vertex positive waves of which I through V are evaluated. These waves, labeled with Roman numerals in Jewett and Williston convention, occur in the first 10 milliseconds after onset of an auditory stimulus. The ABR is considered an exogenous response because it is dependent upon external factors.
Cochlear is a medical device company that designs, manufactures, and supplies the Nucleus cochlear implant, the Hybrid electro-acoustic implant and the Baha bone conduction implant.
Electric acoustic stimulation (EAS) is the use of a hearing aid and a cochlear implant technology together in the same ear. EAS is intended for people with high-frequency hearing loss, who can hear low-pitched sounds but not high-pitched ones. The hearing aid acoustically amplifies low-frequency sounds, while the cochlear implant electrically stimulates the middle- and high-frequency sounds. The inner ear then processes the acoustic and electric stimuli simultaneously, to give the patient the perception of sound.
An auditory brainstem implant (ABI) is a surgically implanted electronic device that provides a sense of sound to a person who is profoundly deaf, due to retrocochlear hearing impairment. In Europe, ABIs have been used in children and adults, and in patients with neurofibromatosis type II.
Nelson Yuan-Sheng Kiang was the founder and former director of the Eaton-Peabody Laboratory of Auditory Physiology at the Massachusetts Eye and Ear Infirmary and professor emeritus of Otology and Laryngology at the Harvard Medical School and also professor emeritus at the Massachusetts Institute of Technology. He was also emeritus in Neurology at the Massachusetts General Hospital and a trustee of the Massachusetts Eye and Ear Infirmary.
Neurostimulation is the purposeful modulation of the nervous system's activity using invasive or non-invasive means. Neurostimulation usually refers to the electromagnetic approaches to neuromodulation.
A direct acoustic cochlear implant - also DACI - is an acoustic implant which converts sound in mechanical vibrations that stimulate directly the perilymph inside the cochlea. The hearing function of the external and middle ear is being taken over by a little motor of a cochlear implant, directly stimulating the cochlea. With a DACI, people with no or almost no residual hearing but with a still functioning inner ear, can again perceive speech, sounds and music. DACI is an official product category, as indicated by the nomenclature of GMDN.
Ingeborg J. Hochmair-Desoyer is an Austrian electrical engineer and the CEO and CTO of hearing implant company MED-EL. Dr Hochmair and her husband Prof. Erwin Hochmair co-created the first micro-electronic multi-channel cochlear implant in the world. She received the Lasker-DeBakey Clinical Medical Research Award for her contributions towards the development of the modern cochlear implant. She also received the 2015 Russ Prize for bioengineering.
TheRoyal Victorian Eye and Ear Hospital is a specialist public teaching hospital in East Melbourne, Australia. It is the only hospital in Australia which specialises in both ophthalmology and otolaryngology.
The Bionics Institute is a medical research institute focusing on medical device development. It is located in Melbourne, Australia.
Claude-Henri Chouard is a French surgeon born on 3 July 1931 in the 15th arrondissement of Paris, this Otologist has been a full member of the Académie Nationale de Médecine since 1999. He was director of the AP-HP Laboratory of Auditory Prosthesis and director of the ENT Research Laboratory at Paris-Saint-Antoine University Hospital from 1967 to 2001. He was also head of the institution's ENT Department from 1978 to 1998. In 1982, he was elected a member of the International Collegium ORL-AS. He achieved worldwide recognition in the late 1970s thanks to the work completed by his Paris laboratory's multidisciplinary team on the multichannel cochlear implant. This implanted electronic hearing device was developed at Saint-Antoine and alleviates bilateral total deafness. When implanted early in young children, it can also help overcome the spoken language problems associated with deafness.
Monita Chatterjee is an auditory scientist and the Director of the Auditory Prostheses & Perception Laboratory at Boys Town National Research Hospital. She investigates the basic mechanisms underlying auditory processing by cochlear implant listeners.
Robert V. Shannon is Research Professor of Otolaryngology-Head & Neck Surgery and Affiliated Research Professor of Biomedical Engineering at University of Southern California, CA, USA. Shannon investigates the basic mechanisms underlying auditory neural processing by users of cochlear implants, auditory brainstem implants, and midbrain implants.
Debara Lyn Tucci is an American otolaryngologist, studying ear, nose, and throat conditions. She co-founded the Duke Hearing Center and currently serves as a professor of Surgery and Director of the Cochlear Implant Program at Duke University. In September 2019 she became Director of the National Institute on Deafness and Other Communication Disorders, one of the National Institutes of Health's 27 Institutes and Centers.
Richard Charles Dowell is an Australian audiologist, academic and researcher. He holds the Graeme Clark Chair in Audiology and Speech Science at University of Melbourne. He is a former director of Audiological Services at Royal Victorian Eye and Ear Hospital.
Professor Clark had a big idea and took it through a torturous scientific and regulatory path to create a device that has transformed the lives of people around the world. His ideas have seeded many other initiatives in bionics
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