A multi-disciplinary approach to understanding and improving hearing by cochlear implant users

Cochlear implants (CIs) restore hearing by electrically stimulating the auditory nerve. This allows many CI users to understand speech well in quiet, but even the most successful have poor pitch perception and struggle in noisy situations. We believe there are two main reasons for these limitations. (i) Although it is possible to elicit different pitches by stimulating different electrodes, the selectivity of this "place-of-excitation" cue is much worse than in normal hearing (NH). (ii) It is also possible to increase pitch by increasing the pulse rate applied to each electrode, but use of this temporal cue is also much worse than in NH. We will study both of these limitations by performing analogous experiments in cats and humans, using some of the same measures in the two species. This will allow us, for the first time, to link the limitations that occur perceptually to their underlying physiological bases, and to do so even for novel stimulation methods that are not possible with existing clinical CIs. The knowledge gained will allow us to propose and test modifications both to implant design and audiological practice.