The role of intensity discrimination on speech perception with a cochlear implant
To understand speech a listener needs to be able to hear the different frequencies contained in the signal and to hear how they differ in strength from one frequency region to another.
This task requires both the ability to hear changes in intensity in one channel and also to be able to compare intensity differences across channels, regardless of the actual intensities. It has been suggested that these two different abilities have different neural mechanisms.
We are testing this idea with the aim of developing an easy way to predict whether a new implant patient will have difficulty developing speech understanding.
Preliminary data shows that cochlear implant users with good speech perception have excellent ability to detect intensity differences on a single electrode and can also detect small changes of relative intensity differences across two electrode positions: those with poor speech understanding have more difficulty in these tasks. We are continuing to recruit participants who have either good or poor speech perception so that we can evaluate our hypothesis reliably.
If successful in showing high predictive power for speech understanding, the test method will be developed into a clinically-useful tool for prognosis in the clinic, and objective measures of the same abilities will also be developed to evaluate speech understanding development in children with a cochlear implant.
Principal investigator: Professor Colette McKay, Dr Katherine Henshall
Lions, and a veski Senior Innovation Fellowship to Prof McKay