PurposeSome cochlear implant (CI) patients lose their residual hearing during surgery. Two factors that might play a role in residual hearing loss are the change in intracochlear hydraulic pressure and force on the cochlear wall during electrode insertion. The aim of this study is to investigate whether a difference in peak hydraulic pressure and peak force on the cochlear wall exists during a CI electrode insertion with different insertion techniques. Materials and methodsTwenty fresh frozen temporal bones were used. Hydraulic pressure and force on the cochlear wall were recorded during straight electrode insertions with 1) slow versus fast insertion speed, 2) manual versus automatic insertion method and 3) round window approach (RWA) versus extended RWA (ERWA). ResultsWhen inserting with a slow compared to a fast insertion speed, the peak hydraulic pressure is 239% (95% CI: 130–399%) higher with a RWA and 58% (95% CI: 6–137%) higher with an ERWA. However, the peak force on the cochlear wall is a factor 29% less (95% CI: 13–43%) with a slow insertion speed. No effect was found of opening and insertion method. ConclusionsAs contradictory findings were found for hydraulic pressure and force on the cochlear wall on insertion speed, it remains unclear which insertion speed (slow versus fast) is less traumatic to inner ear structure.