Lindsay Devries of University of Washington will be giving a talk on "Optimizing programming in cochlear implant listeners: electrode position, channel interaction and speech perception"

Abstract: Cochlear implants (CIs) are auditory prostheses that electrically stimulate auditory neurons, providing sound to individuals with severe-to- profound hearing loss. However, speech understanding abilities are highly variable among CI listeners. One source of this variability is the electrode-neuron interface, which refers to how well each electrode activates the target auditory neurons. Electrode position, bone and tissue growth, and the integrity of the auditory neurons are factors that may impair transmission of speech information. Prior studies have demonstrated that electrical current level requirements are higher and spread of excitation is broader for electrodes distant from the neurons or those near a region of neural degeneration. Broader spread of excitation increases channel interaction, which can distort spectral information and result in decreased speech understanding. Currently, it is not possible to directly measure neural survival in CI listeners; therefore, obtaining information about electrode position is an alternative approach to assessing the electrode- neuron interface; this information is available through computerized tomography (CT) imaging. However, CT imaging is costly, exposes patients to radiation, and is not readily available to audiologists. Therefore, a behavioral method to assess channel interaction due to distant electrode placement may offer an alternative of this aspect of the electrode-neuron interface. Psychophysical tuning curves (PTC) are a behavioral measurement that has been established as a reliable estimate of channel interaction; broader PTCs may result from a distant electrode, increasing channel interaction in that region of the cochlea. This research had two goals: a) to examine the relationship between CT-estimated electrode distance and PTC spread of excitation, and b) to determine if using spatially focused stimulation on channels predicted to have distant electrode position improves spectral resolution and speech understanding. The results of this study provide an important link between site-specific peripheral measures of the electrode-neuron interface, and the practical application of these measures to CI listener programs.