Teachers notes

Professor Graeme Clark
Otolaryngologist

Contents

Introduction
Summary of career
Extract from interview and focus questions
Activities
Keywords

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Introduction

Professor Graeme Clark was interviewed in 2011 for the Interviews with Australian scientists series. By viewing the interviews in this series or reading the transcripts and extracts, your students can begin to appreciate Australia's contribution to the growth of scientific knowledge and view science as a human endeavour. These interviews specifically tie into the Australian Curriculum sub-strand ‘Nature and development of science’.

The following summary of Professor Clark’s career sets the context for the extract chosen for these teachers’ notes. The extract discusses the mechanism of hearing with respect to place and temporal coding. Use the focus questions that accompany the extract to promote discussion among your students.

Summary of career

Graeme Milbourne Clark was born in Camden, NSW in 1935. He finished his secondary education as a boarder at Scots College in Sydney in 1951. Clark then went to the University of Sydney graduating with honours from an MB, BS degree (1957). Fresh from medical school, Dr Clark worked at the Royal Prince Alfred and North Shore Hospitals as a resident medical officer (1958-59) before specialising as a registrar in neurosurgery and otolaryngology (1961).

Clark then left our sunny shores for England, where he worked as senior house surgeon at the Royal National Throat, Nose & Ear Hospital (1962) and senior registrar in otolaryngology at the Bristol General Hospital (1963). Clark returned to Australia and the Royal Victorian Eye and Ear Hospital as assistant and then senior ENT surgeon (1963-66). He held this position concurrently with ENT surgery positions at the Alfred, Austin and Repatriation General Hospitals (1964-66). Not satisfied with the treatments available to profoundly deaf patients, Clark returned to the University of Sydney to embark on further study. He completed both an MS (1968) and a PhD degree (1969). Clark’s MS research centred on the structural support of the nose in reconstructive surgery. With his PhD work he looked at middle ear and neural mechanisms of hearing, and discovered the limitations in using a single-channel cochlear implant for temporal coding of frequency. He concluded meaningful speech might be understood if it was analysed into its important components, and these used for electrical stimulation. During his studies, Clark also lectured in physiology at the University of Sydney and remained as senior honorary ENT surgeon at the Eye and Ear Hospital, Melbourne.

In 1969, Clark accepted the William Gibson chair of otolaryngology at the University of Melbourne (1970-2004). It was during this period, in 1978, that Clark developed and implanted the first multi-channel cochlear implant. His research during study leave at the University of Keele in 1976 played an important role. Whilst professor of otolaryngology, Clark established the Cochlear Implant Clinic at the Royal Victorian Eye and Ear Hospital and was the surgeon in charge (1985-2004). In 1984 Clark founded the Bionic Ear Institute and acted as its director until 2005. Clark was made laureate professor at the University of Melbourne in 1999, professor at the University of Wollongong in 2003 and distinguished professor at La Trobe University in 2008. He is now distinguished researcher at the ICT for Life Sciences.

Professor Clark has received numerous awards recognising his contributions to science and the community. Some of these include officer of the Order of Australia (1983), James Cook medal from the Royal Society of NSW (1992), Clunies Ross National Science and Technology award (1993),Sir William Upjohn medal from the University of Melbourne (1997), fellow of the Australian Academy of Technological Sciences and Engineering (1998), Victoria Prize (1999), Senior Australian of the Year (2001), honorary member of the American Otological Society (2002), honorary fellow of the Royal Society of Medicine (2003), companion of the Order of Australia (2004), Prime Minister’s Prize for Science (2004), honorary fellow of the Royal College of Surgeons of England (2004), fellow of the Royal Society London (2004), International Speech Communication Association medal (2005), Charles Holland Foundation International Prize in Audiology (2005), Ian Wark medal (2006), Zülch Prize from the Max Planck Society (2007), Lifetime Achievement award from Monash University (2007), Otto Schmitt award from the International Federation of Medical and Biological Engineering (2009), Lister medal from the Royal College of Surgeons of England (2010),  Zotterman medal from the Nobel Institute for Neurophysiology, Karolinska Institutet (2011) and the CSL Florey medal (2011).

Professor Clark received honorary doctorates in medicine from Medizinische Hochschule, Hanover (1988) and the University of Sydney (1989), in science from the University of Wollongong in (2002), in engineering from CYC University Taiwan (2003) and in law from Monash University (2004) and Zaragoza University (2010). Other honours include the naming of the Graeme Clark Centre for Innovation in the Sciences at The Scots College in Sydney and the Graeme Clark Research Institute in Tabor College, Adelaide.

Professor Clark was elected to the fellowship of the Australian Academy of Science in 1998.

 

Extract from interview

Place coding

As your PhD evolved, you no doubt became aware of other people working in the field. Can you tell us about the evolution of your thoughts on cochlear implantation at that time?

Yes. At first it was a learning experience in how the ear functioned. We are not taught, even when doing a fellowship in general surgery, a lot about the ear. So firstly I had to learn about how the brain functioned. It was clear, from early work that was just emerging from Nelson Kiang, Jerzy Rose and others that the ear was functioning on a place-coding basis. It wasn’t just getting timing information. That was a very important lesson that I learned when I did neurophysiology. I was surprised that many of the clinicians who were starting to take an interest in this area hadn’t really based it on a lot of fundamental research. I feel very strongly that good clinical research should always be underpinned by experimental researches. So, I guess, that’s the way I went. I went to see how to do the research experimentally and how that would affect the clinical outcomes and to try and keep the two in balance.

Even when you were doing a PhD, the idea of place coding was in your mind?

Well, it emerged. The first thing that I did and aimed to do with my research was to see whether or not the single channel system would work. That was the system that was being promulgated in the clinical domain. In other words, would timing alone through a single channel implant be enough to convey speech? It may seem surprising now but, in 1966-67, neurophysiologists weren’t sure which code would work. Coding frequencies, for example, whether a simple place code or a simple temporal code was the key and what frequencies they applied to. So my first challenge was to see whether electrical stimulation could reproduce the temporal coding sufficiently well to allow a single-channel device to be used. When I found that it didn’t, I realised that one had to do studies to look at place coding. I could see too that it was going to be essential to select out important frequencies of speech and try to get them to be perceived through place and temporal coding – these two systems for coding sound.

The intellectual team

Who were the key people who worked with you to do the intellectual work?

The three of us who worked on it were Joe Tong, with whom I worked very closely, Bruce Millar from Canberra and me. We met and talked often about it. In addition, Jim Patrick and Ian Forster helped with the electronics, but it was the three of us who worked through the questions. Bruce Millar, who had been one of the students and postdocs of Bill Ainsworth, with whom I had worked at Keele University, was now a very good speech scientist. I had supervised Joe initially on developing models of how cochlears function. It was only when we had implanted a patient that I was able to work with Joe and develop an engineering type approach to psychophysics. But we really complemented each other.

I had personally been helped by having taken study leave, when the telethon was on, to work with a speech science laboratory at Keele University in the UK. My project was on formant analyses of fricative sounds like ‘v’, ‘s’ and ‘th’. I had felt that one of the keys to all this was to understand speech, and in the Department we knew so little then about speech. I had this feeling that the key was not physiology alone, which is what I had set out to do, but it would be speech science. It turned out, for me, to be a very helpful approach. I came back from Keele in 1976 with a very strong interest in formants, which are key elements of speech. None of us knew much about formants. When I examined audiology students on formants, they said it was a very strange and unfair question. Of course, it is not now.

An edited transcript of the full interview can be found at http://www.science.org.au/scientists/interviews/c/clark.html.

Focus questions

  • What are the two systems which together code for sound?
  • Define place coding and temporal coding. [Students may need access to a medical dictionary or the internet]
  • What does Clark advocate should underpin clinical work? Why?
  • ‘Formants’ can be described as resonance in the vocal tract. What is resonance in the vocal tract and how was this important in developing the cochlear implant?

Activities

Select activities that are most appropriate for your lesson plan or add your own. These activities align with the Australian Curriculum strands ‘Science Understanding’, ‘Science as a Human Endeavour’ and ‘Science Inquiry Skills’, as well as the New South Wales syllabus Stage 6 Senior Science outcome 9.3.1 and Stage 6 Biology outcome 9.5.6. You can also encourage students to identify key issues in the preceding extract and devise their own questions or topics for discussion.

  • Australian Academy of Science
    • Cochlear implants – wiring for sound This Nova: science in the news topic discusses the function of the ear, hearing loss and the development of the cochlear implant. Activities, further reading and useful sites sections are included. (ACSHE158) (ACSHE161)
    • Rebuilding humans using bionics Another Nova: science in the news topic which investigates a range of medical bionic technologies including bionic hearts, eyes, limbs, ears and brains. (ACSHE158) (ACSHE161)
    • Spare parts PrimaryConnections science background resource for teachers.
  • How Sound Travels (Science and Mathematics Initiative for Learning Enhancement, Illinois Institute of Technology, USA) Students investigate whether sound travels more effectively through a solid, liquid or gas. (ACSSU182) (ACSIS164) (ACSIS170)
  • The science of acoustics (Acoustical Society of America) This comprehensive site includes games, science fair projects, activities, lesson plans and posters about the science of sound.
  • Do You Hear What I Hear? (National Institutes of Health, USA) Part of the ‘How your brain understands what your ears hear’ module for years 7-8 students. This lesson involves an exploration of pitch, loudness and perception of sound. Resources include teachers’ notes, student masters and links to activity supplements.
  • Make your own vowel resonators! (Mark Huckvale, University College London) A fun practical exercise to model the shape the vocal tract forms to make the sounds ‘ah’, ‘ih’ and ‘oo’. (ACSSU182)
  • Cochlear Implant (Powerhouse Museum, NSW) Provides extensive information on cochlear implants with associated activities throughout the site. This site was designed to link into the NSW HSC syllabi for Engineering, Design and Technology and Information processing. (ACSHE158)
  • A History of Innovation (CochlearTM, Australia) Interactive timeline of the development of the Cochlear implant. (ACSHE158) (ACSHE161)
  • Two pages on the Graeme Clark Foundation website are devoted to answering How the ear functions in health and disease and How the cochlear implant (bionic ear) functions. Have students ask their own questions about ear function and pathology. Students can answer these questions using library and internet resources. (ACSIS174)
    • Ask students to perform an investigation to explore one of the scientific principles used in the cochlear implant. For example sound, resonance or magnetic induction.
    • Repeat the classic experiment performed by Robert Hooke relating pitch and frequency. Place a card against the teeth of a spinning wheel and note how the pitch increases with speed.
    • Investigate standing waves using a rope attached to a fixed point.
    • Explore the perception of loudness. Use a sound level meter (which measures sound pressure level) and determine the relationship between physical sound levels, human perception of loudness and how this varies with pitch. [Students might want to make reference to the power law, Weber-Fechner law and the idea of ‘just noticeable difference’]
    • Conduct an experiment into the relationship between frequency and resonance in a closed-end air column. Blow gently across the top of a glass bottle with a narrow neck. Vary the fluid level and your record observations. Relate this to what happens in the mouth when making vowel sounds.
    • Research the famous work of Michael Faraday on the transmission of electrical energy with inductive coupling. What are the advantages in using this kind of power transmission for the cochlear implant? (ACSIS125) (ACSIS126) (ACSIS129) (ACSIS130)

Keywords

cochlear implant
ear
formant
multi-channel
place-coding
resonance
single-channel
sound
speech
temporal

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