Our researchers are investigating why some cochlear implant recipients are unable to understand speech as well as others.

  • Our research so far shows that for many cochlear implant users, there are regions of poor nerve survival, auditory brain pathway difficulties and brain changes due to deafness.
  • We aim to determine the best cochlear implant processing features and hearing therapies for each person after they get their implant, so that they get the maximum benefit from their implant.

Why is individual optimisation needed for cochlear implant recipients?

Our goal is to understand why some recipients of the cochlear implant do not understand speech as well as others.

There are three main mechanisms that have been associated with poor benefit from a cochlear implant:

  • Uneven or poor survival of auditory neurons in the inner ear
  • Difficulty processing information in the auditory brain pathways
  • Detrimental brain changes because of deafness.

We have recruited 30  participants so far and published two papers that showed the brain regions that respond strongly when people are listening to a story, and how those differ for very new cochlear implant users.

Next steps for Bionics Institute researchers

Our preliminary data comparing two different ways to estimate the pattern of neural survival in the cochlea (electrophysiology and behavioural measurements) show that for many cochlear implant users, there are regions of very poor nerve survival, and that both methods can locate these regions.

The next steps are to use this information to re-program the implant to avoid these areas in the cochlea to improve speech perception.

The research team

Bionics Institute team: Professor Colette McKay, Dr Tommy Peng and Mica Haneman.
Clinical collaborators: Dr Maureen Shader and Dr Robert Luke.
PhD student: Jamal Esmaelpoor


Shader, M. J., Luke, R., Gouailhardou, N., & McKay, C. M. (2021). The use of broad vs restricted regions of interest in functional near-infrared spectroscopy for measuring cortical activation to auditory-only and visual-only speech. Hearing Research, 406, 108256. https://doi.org/10.1016/j.heares.2021.108256

Zhou, X., Seghouane, A. K., Shah, A., Innes-Brown, H., Cross, W., Litovsky, R., & McKay, C. M. (2018). Cortical speech processing in postlingually deaf adult cochlear implant users, as revealed by functional near-infrared spectroscopy. Trends in hearing, 22, 2331216518786850. https://doi.org/10.1177/2331216518786850