Objectives: To optimize patient's maps in Electric Acoustic Stimulation (EAS) users based on the degree of post-operative aided hearing thresholds.
Methods: Twenty-one adult EAS patients participated in this study. Patients were subdivided into three groups, based on their unaided hearing threshold: (1) electric complementary (EC, n = 6) patients with ≤30 dB HL at 125-500 Hz with severe to profound hearing loss at higher frequencies who only use electric stimulation, (2) EAS (n = 8) patients with 30-70 dB HL from 125 to 250 Hz and profound hearing loss in high frequencies who use combined EAS, and (3) Marginal-EAS (M-EAS, n = 7) patients with 70-95 dB HL at frequencies ≤250 Hz who use combined EAS. Sentence perception in noise, melodic contour identification, and subjective preference were measured using Full Overlap, Narrow Overlap, Gap, and Meet maps.
Result: Of the 21 patients that participated, 12 subjects were classified as complete hearing preservation and 9 subjects were classified as partial hearing preservation. The highest performing maps in sentence-in-noise perception and melodic contour identification were Gap, Meet, and Full Overlap for the EC, EAS, and the M-EAS groups, respectively. These results are consistently across different test materials and align with subject preference as well.
Conclusion: These results suggest that clinical fitting in EAS listening should be individually tailored. EAS performance can be enhanced by optimizing maps between acoustic and electric stimulation based on the degree of aided hearing thresholds.
Keywords: Cochlear implant; EAS frequency maps; EAS subject grouping; Electric acoustic stimulation; Speech perception in EAS.