Munich university models processor-based cochlear implants
Researchers at the Technische Universitaet Muenchen (TUM) are working to overcome current limits of cochlear implants technology by investigating the implementation of signals in the auditory nerve and the subsequent neuronal processing in the brain.
The Munich-based university if developing computer models to help manufacturers of cochlear implants improve their devices.
Cochlear implants consist of a speech processor and a transmitter coil worn behind the ear, together with the actual implant, an encapsulated microprocessor placed under the skin to directly stimulate the auditory nerve via an electrode with up to 22 contacts.
“Getting implants to operate more precisely will require strategies that are better geared to the information processing of the neuronal circuits in the brain. The prerequisite for this is a better understanding of the auditory system,” explains Professor Werner Hemmert, director of the Department for Bio-Inspired Information Processing, at the TUM Institute of Medical Engineering (IMETUM).
Based on physiological measurements of neurons, his working group successfully built a computer model of acoustic coding in the inner ear and the neuronal information processing by the brain stem. This model will allow the researchers to further develop coding strategies and test them in experiments on people with normal hearing, as well as people carrying implants.
A major challenge is restoring spatial hearing. Since our ears are located a few centimeters apart, sound waves form a given source generally reach one ear before the other. The difference is only a few millionths of a second, but that is enough for the brain to localize the sound source.
A microprocessor has a fast enough response time, but a nerve impulse takes around one hundred times longer. To achieve a perfect interplay, new strategies need to be developed.
“Many ideas can now be tested significantly faster. Then only the most promising processes need to be evaluated in cumbersome patient trials,” says Werner Hemmert. The new models thus have the potential to significantly reduce development cycles. “In this way, patients will benefit from better devices sooner.”