Research related to Cochlear Implants

The cochlear implant ('bionic ear') converts sound into electrical pulses which are injected directly into the auditory nerves. It works well for speech, but less well for music. In collaboration with Cochlear Ltd, we are conducting research and development of coding strategies for auditory information to be used in cochlear implants to improve the appreciation of music by users. Such improvements should also lead to improvements in the perception of tonal languages.

The first part of this study was to make a 'map' relating the electrical variables on the signals input to the electrodes to the musical perceptions of the user. This was the first part of the doctoral research project of Robert Fearn and is reported in

and in a technical article: Fearn, R., Carter, P. and Wolfe, J. (1999) 'The perception of pitch by users of cochlear implants: possible significance for rate and place theories of pitch', Acoustics Australia, 27 (2) 41-43 .

Robert Fearn's thesis is now available in pdf format (3.3 Mbyte):

Our collaboration with Cochlear led to the development of a new processing strategy called Multirate, which is described by the patent:

  • Wolfe, J., Carter, P., Parker, S., Fearn, R., and Frampton, N. (2001) Multirate cochlear stimulation strategy and apparatus. (International publication date: 18/1/2001; priority date: 13/7/1999). Australia (App'n No 56652/00), Canada (TBA), Japan (TBA), US (TBA) and Europe (Appn No 00941808.8)
Robert implemented the multirate strategy with two different sets of parameter compromises, called Voc-L and Instrument-L (and collectively Music-L). Essentially they assign different importance to the frequency information needed for speech and for music.

Multirate currently only runs on a developmental hardware platform that was developed by the Bionic Ear Institute and the Cooperative Research Centre for Cochlear Implant and Hearing Innovation in Melbourne.

CI subject performing automated pitch perception experiment

CI subject performing automated pitch perception experiment


Robert Fearn won the silver medal in the international Young Inventors Award for his work on this project. (See the story in the Far Eastern Economic Review.)

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