Electric acoustic stimulation (EAS) with the Naída CI Q90 sound processor in experienced cochlear implant users

Objectives: The benefit of using the electroacoustic functionality was tested compared to electric stimulation alone. Two different cut-off frequencies between acoustic and electric stimulation were tried. Methods: Performance and subjective preference in 10 subjects was measured with electric only and electroacoustic stimulation with two settings: a cut-off for acoustic amplification at the frequency where thresholds exceeded 70 dB and 85 dB. An overlapping setting was also tried in five participants. Results: There was a non-significant trend with a median improvement in SRT of 1.3 dB (70 dB cut-off) and 0.8 dB (85 dB cut-off) compared to the electric only condition. From nine subjects who completed the study, one preferred the 85 dB cut-off frequency, with the others preferred either a 70 dB cut-off or an overlapping setting. Discussion: Nine subjects continued to use the EAS processor after study termination because of subjective benefits. The variability in speech outcomes and subjective preference is underlining the importance of being able to manually change acoustic and electric cut-off frequencies. Conclusion: There were non-significant median group benefits from use of the acoustic component for these existing CI users. A hearing loss of 70 dB HL is an appropriate default cut-off frequency in the fitting software.