ECAP, ESR and Subjective Levels for Two Different Nucleus 24 Electrode Arrays

Objective: We compared behavioral judgment of maximum comfortable loudness levels (C levels) and behavioral thresholds (Ts) for straight and Contour electrode arrays with two objective thresholds, electrically elicited stapedial reflex thresholds (eSRTs) and electrically elicited compound action potential thresholds (eCAP thresholds), on experienced adult cochlear implant users. Next, we evaluated the predictive value of objective measures for the straight and Contour electrode arrays, respectively. Study Design: This is a prospective, two-group comparison study of two objective and subjective levels for two different Nucleus 24 electrode arrays. Patients: Thirty experienced adults with Nucleus 24 cochlear implant were subjects in this study. Half the subjects used the straight electrode array, and the other half used the Contour electrode array. Methods: Subjective C levels, Ts, and eSRTs were successfully identified for each active electrode. eCAP thresholds were measured on 5 representative basal, medial, and apical electrodes. Correlation and regression analyses between subjective levels and objective thresholds were performed. Results: For our study subjects, there were no significant differences between the straight and Contour electrode array in regard to stimulation requirements between C levels, Ts, and thresholds of eCAP thresholds and eSRTs. Conclusion: Both eSRTs and eCAP thresholds may be used equally for estimation of subjective levels for either straight electrode array or Contour electrode array.