Diagnosing regions of poor cochlear health in cochlear implant users
Sensorineural hearing loss can often cause a loss of auditory nerve cells after the hair cells in the inner ear are damaged. This loss of nerve cells can occur in patches along the cochlea called ‘dead regions’, and these dead regions lead to a smearing of information in the speech sounds for users of cochlear implants.
If we know who has these dead regions and where they are, we can use this information when programming the sound processor to avoid these regions and the information can also be used to help automatic programming of the sound processor. Currently there is now way to find these regions in cochlear implant users.
In this project we are measuring the response of the auditory nerve (electrically-evoked compound action potential) to current pulses at different electrode locations, using a technique called NRT in a group of cochlear implant users. We are varying the current pulse duration and interphase gap duration and measuring the effect on the nerve response.
This effect has been hypothesized to be correlated with nerve survival density. So far, the results have shown that the effect is correlated with another factor (the effect of rate of stimulation on threshold), which is thought to be also related to nerve survival density.
We are now using this information to improve the way that cochlear implants can be automatically and objectively programmed for young infants, as well as applying it to the optimization of speech processor programs for all implant users.
Principal investigator – Prof Colette McKay
veski Senior Innovation Fellowship to Prof McKay