Determining whether electrodes are sitting within the cochlea can be difficult as the checks run by the programming software cannot always determine this. In some cases, patients may be unable to give the audiologist detailed feedback which can complicate the issue further. However, it is important for the audiologist to know which (if any) electrodes to switch off during programming because they are extra-cochlear. Currently, these patients may be referred for an X-ray or cone-beam CT scan to help determine how many electrodes are in the cochlea, which subjects the patient to radiation. Finding a quick reliable method for audiologists to determine which electrodes are within the cochlea would be valuable. The team in Southampton, UK, have used surface electrodes to REVS to establish if electrodes were in the cochlea on 17 adult Nucleus CI users. Initially they examined if the test was reliable and if differences were found according to stimulation mode, stimulation level and electrode position of both the CI and surface electrodes. The measures were found to be quick and repeatable. They also found that electrode voltages (EVs) differed for those electrode arrays found in the cochlea compared to those outside. They also investigated whether intra-cochlear electrodes which were deactivated had an effect. Although this group differed from the control group, it also differed from the extra-cochlear electrode group. Therefore, this test could be used to detect extra-cochlea electrodes/electrode migration. As this test is rapid and reliable and required no patient feedback, it could be a useful clinical tool for programming cochlear implants.