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Now that sounds better

Monday, 10 September 2007
Author: University of South Australia

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A UniSA researcher and his overseas colleagues are hoping to improve what cochlear implant patients hear with a different aid - mathematics.

The cochlear implant, an Australian invention, has changed the lives of 100,000 deaf people worldwide.

Few people realise, however, that the device is not a cure for deafness - it is only an artificial substitute for hearing, and an imperfect one at that. Some cochlear implant patients, unable to clearly identify speech in every setting, still rely on lip-reading, and the pleasure of listening to music eludes most.

Postdoctoral Fellow Dr Mark McDonnell is applying information theory to biology to better understand how human sensory systems work, thanks to a three-year Australian Research Council Discovery grant.

"The project aims to discover how biological sensory systems encode stimuli - such as things we hear and see - into electrical activity that the brain can use," Dr McDonnell said from his office at UniSA's Institute for Telecommunications Research.

Based on their earlier work in which they determined why it might be useful for different nerves to be triggered randomly by fluctuations of the hair cells in the inner ear, Dr McDonnell and colleagues at the UK's University of Warwick are looking at ways to replicate these random fluctuations in cochlear implant patients.

"We believe this variability has a central role in allowing our ears to function so well," Dr McDonnell said.

"By making the electrical signals that cochlear implants produce more like natural, healthy electrical signals, we hope to improve the quantity and quality of what patients can hear.

"It is all about introducing randomness in a controlled way."

Dr McDonnell said his research will also look at how the brain effectively and usefully throws away bits of information it doesn't actually need to achieve some task.

"It makes sense if the ear only encodes sounds to the degree of accuracy the brain needs to actually comprehend it clearly, or discriminate different sounds clearly," he said.

The concept may have much wider application in the future.

"I think understanding this would be a key to future biomedical prosthetics, such as bionic eyes."

Dr McDonnell is one of 16 early-career scientists who took part in last month's Fresh Science, a national program to promote new research to the public sponsored by the Federal and Victorian Governments.


Dr Mark McDonnell (email)
Institute for Telecommunications Research
University of South Australia
Business: (08) 8302 3341
Fax: (08) 8302 3817